# How do you find the sum of the arithmetic sequence having the data given #a_1=7#, d = - 3, n = 20?

The sum

By signing up, you agree to our Terms of Service and Privacy Policy

TheThe sumThe sum ( S ) of an arithmetic sequence canThe sum ofThe sum ( S ) of an arithmetic sequence can beThe sum of anThe sum ( S ) of an arithmetic sequence can be foundThe sum of an arithmetic sequenceThe sum ( S ) of an arithmetic sequence can be found using the formula:

The sum of an arithmetic sequence canThe sum ( S ) of an arithmetic sequence can be found using the formula:

[ SThe sum of an arithmetic sequence can beThe sum ( S ) of an arithmetic sequence can be found using the formula:

[ S = \The sum of an arithmetic sequence can be foundThe sum ( S ) of an arithmetic sequence can be found using the formula:

[ S = \frac{nThe sum of an arithmetic sequence can be found using the formulaThe sum ( S ) of an arithmetic sequence can be found using the formula:

[ S = \frac{n}{The sum of an arithmetic sequence can be found using the formula:

The sum ( S ) of an arithmetic sequence can be found using the formula:

[ S = \frac{n}{2The sum of an arithmetic sequence can be found using the formula:

[ S_n =The sum ( S ) of an arithmetic sequence can be found using the formula:

[ S = \frac{n}{2}(The sum of an arithmetic sequence can be found using the formula:

[ S_n = \fracThe sum ( S ) of an arithmetic sequence can be found using the formula:

[ S = \frac{n}{2}(aThe sum of an arithmetic sequence can be found using the formula:

[ S_n = \frac{nThe sum ( S ) of an arithmetic sequence can be found using the formula:

[ S = \frac{n}{2}(a_The sum of an arithmetic sequence can be found using the formula:

[ S_n = \frac{n}{2The sum ( S ) of an arithmetic sequence can be found using the formula:

[ S = \frac{n}{2}(a_1 +The sum of an arithmetic sequence can be found using the formula:

[ S_n = \frac{n}{2}(The sum ( S ) of an arithmetic sequence can be found using the formula:

[ S = \frac{n}{2}(a_1 + aThe sum of an arithmetic sequence can be found using the formula:

[ S_n = \frac{n}{2}(aThe sum ( S ) of an arithmetic sequence can be found using the formula:

[ S = \frac{n}{2}(a_1 + a_nThe sum of an arithmetic sequence can be found using the formula:

[ S_n = \frac{n}{2}(a_The sum ( S ) of an arithmetic sequence can be found using the formula:

[ S = \frac{n}{2}(a_1 + a_n)The sum of an arithmetic sequence can be found using the formula:

[ S_n = \frac{n}{2}(a_1The sum ( S ) of an arithmetic sequence can be found using the formula:

[ S = \frac{n}{2}(a_1 + a_n) \The sum of an arithmetic sequence can be found using the formula:

[ S_n = \frac{n}{2}(a_1 +The sum ( S ) of an arithmetic sequence can be found using the formula:

[ S = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S ) is the sum ofThe sum of an arithmetic sequence can be found using the formula:

[ S_n = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S_nThe sum ( S ) of an arithmetic sequence can be found using the formula:

[ S = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S ) is the sum of theThe sum of an arithmetic sequence can be found using the formula:

[ S_n = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S_n \The sum ( S ) of an arithmetic sequence can be found using the formula:

[ S = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S ) is the sum of the sequenceThe sum of an arithmetic sequence can be found using the formula:

[ S_n = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S_n )The sum ( S ) of an arithmetic sequence can be found using the formula:

[ S = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S ) is the sum of the sequence The sum of an arithmetic sequence can be found using the formula:

[ S_n = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S_n ) isThe sum ( S ) of an arithmetic sequence can be found using the formula:

[ S = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S ) is the sum of the sequence
- ( n ) is the number of terms The sum of an arithmetic sequence can be found using the formula:

[ S_n = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S_n ) is the sumThe sum ( S ) of an arithmetic sequence can be found using the formula:

[ S = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S ) is the sum of the sequence
- ( n ) is the number of terms
- ( aThe sum of an arithmetic sequence can be found using the formula:

[ S_n = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S_n ) is the sum of theThe sum ( S ) of an arithmetic sequence can be found using the formula:

[ S = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S ) is the sum of the sequence
- ( n ) is the number of terms
- ( a_The sum of an arithmetic sequence can be found using the formula:

[ S_n = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S_n ) is the sum of the first ( n ) terms, -The sum ( S ) of an arithmetic sequence can be found using the formula:

[ S = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S ) is the sum of the sequence
- ( n ) is the number of terms
- ( a_1The sum of an arithmetic sequence can be found using the formula:

[ S_n = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S_n ) is the sum of the first ( n ) terms,
- ( a_1The sum ( S ) of an arithmetic sequence can be found using the formula:

[ S = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S ) is the sum of the sequence
- ( n ) is the number of terms
- ( a_1 )The sum of an arithmetic sequence can be found using the formula:

[ S_n = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S_n ) is the sum of the first ( n ) terms,
- ( a_1 \The sum ( S ) of an arithmetic sequence can be found using the formula:

[ S = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S ) is the sum of the sequence
- ( n ) is the number of terms
- ( a_1 ) is theThe sum of an arithmetic sequence can be found using the formula:

[ S_n = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S_n ) is the sum of the first ( n ) terms,
- ( a_1 )The sum ( S ) of an arithmetic sequence can be found using the formula:

[ S = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S ) is the sum of the sequence
- ( n ) is the number of terms
- ( a_1 ) is the first term
- ( a_n ) isThe sum of an arithmetic sequence can be found using the formula:

[ S_n = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S_n ) is the sum of the first ( n ) terms,
- ( a_1 ) is the first termThe sum ( S ) of an arithmetic sequence can be found using the formula:

[ S = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S ) is the sum of the sequence
- ( n ) is the number of terms
- ( a_1 ) is the first term
- ( a_n ) is theThe sum of an arithmetic sequence can be found using the formula:

[ S_n = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S_n ) is the sum of the first ( n ) terms,
- ( a_1 ) is the first term of theThe sum ( S ) of an arithmetic sequence can be found using the formula:

[ S = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S ) is the sum of the sequence
- ( n ) is the number of terms
- ( a_1 ) is the first term
- ( a_n ) is the ( nThe sum of an arithmetic sequence can be found using the formula:

[ S_n = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S_n ) is the sum of the first ( n ) terms,
- ( a_1 ) is the first term of the sequence, The sum ( S ) of an arithmetic sequence can be found using the formula:

[ S = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S ) is the sum of the sequence
- ( n ) is the number of terms
- ( a_1 ) is the first term
- ( a_n ) is the ( n \The sum of an arithmetic sequence can be found using the formula:

[ S_n = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S_n ) is the sum of the first ( n ) terms,
- ( a_1 ) is the first term of the sequence,
- ( aThe sum ( S ) of an arithmetic sequence can be found using the formula:

[ S = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S ) is the sum of the sequence
- ( n ) is the number of terms
- ( a_1 ) is the first term
- ( a_n ) is the ( n )th termThe sum of an arithmetic sequence can be found using the formula:

[ S_n = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S_n ) is the sum of the first ( n ) terms,
- ( a_1 ) is the first term of the sequence,
- ( a_nThe sum ( S ) of an arithmetic sequence can be found using the formula:

[ S = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S ) is the sum of the sequence
- ( n ) is the number of terms
- ( a_1 ) is the first term
- ( a_n ) is the ( n )th term

The sum of an arithmetic sequence can be found using the formula:

[ S_n = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S_n ) is the sum of the first ( n ) terms,
- ( a_1 ) is the first term of the sequence,
- ( a_n \The sum ( S ) of an arithmetic sequence can be found using the formula:

[ S = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S ) is the sum of the sequence
- ( n ) is the number of terms
- ( a_1 ) is the first term
- ( a_n ) is the ( n )th term

Given: The sum of an arithmetic sequence can be found using the formula:

[ S_n = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S_n ) is the sum of the first ( n ) terms,
- ( a_1 ) is the first term of the sequence,
- ( a_n ) isThe sum ( S ) of an arithmetic sequence can be found using the formula:

[ S = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S ) is the sum of the sequence
- ( n ) is the number of terms
- ( a_1 ) is the first term
- ( a_n ) is the ( n )th term

Given:

- (The sum of an arithmetic sequence can be found using the formula:

[ S_n = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S_n ) is the sum of the first ( n ) terms,
- ( a_1 ) is the first term of the sequence,
- ( a_n ) is theThe sum ( S ) of an arithmetic sequence can be found using the formula:

[ S = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S ) is the sum of the sequence
- ( n ) is the number of terms
- ( a_1 ) is the first term
- ( a_n ) is the ( n )th term

Given:

- ( a_1 = 7 \The sum of an arithmetic sequence can be found using the formula:

[ S_n = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S_n ) is the sum of the first ( n ) terms,
- ( a_1 ) is the first term of the sequence,
- ( a_n ) is the (The sum ( S ) of an arithmetic sequence can be found using the formula:

[ S = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S ) is the sum of the sequence
- ( n ) is the number of terms
- ( a_1 ) is the first term
- ( a_n ) is the ( n )th term

Given:

- ( a_1 = 7 ) The sum of an arithmetic sequence can be found using the formula:

[ S_n = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S_n ) is the sum of the first ( n ) terms,
- ( a_1 ) is the first term of the sequence,
- ( a_n ) is the ( n )-th term ofThe sum ( S ) of an arithmetic sequence can be found using the formula:

[ S = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S ) is the sum of the sequence
- ( n ) is the number of terms
- ( a_1 ) is the first term
- ( a_n ) is the ( n )th term

Given:

- ( a_1 = 7 )
- (The sum of an arithmetic sequence can be found using the formula:

[ S_n = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S_n ) is the sum of the first ( n ) terms,
- ( a_1 ) is the first term of the sequence,
- ( a_n ) is the ( n )-th term of theThe sum ( S ) of an arithmetic sequence can be found using the formula:

[ S = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S ) is the sum of the sequence
- ( n ) is the number of terms
- ( a_1 ) is the first term
- ( a_n ) is the ( n )th term

Given:

- ( a_1 = 7 )
- ( dThe sum of an arithmetic sequence can be found using the formula:

[ S_n = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S_n ) is the sum of the first ( n ) terms,
- ( a_1 ) is the first term of the sequence,
- ( a_n ) is the ( n )-th term of the sequenceThe sum ( S ) of an arithmetic sequence can be found using the formula:

[ S = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S ) is the sum of the sequence
- ( n ) is the number of terms
- ( a_1 ) is the first term
- ( a_n ) is the ( n )th term

Given:

- ( a_1 = 7 )
- ( d =The sum of an arithmetic sequence can be found using the formula:

[ S_n = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S_n ) is the sum of the first ( n ) terms,
- ( a_1 ) is the first term of the sequence,
- ( a_n ) is the ( n )-th term of the sequence, The sum ( S ) of an arithmetic sequence can be found using the formula:

[ S = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S ) is the sum of the sequence
- ( n ) is the number of terms
- ( a_1 ) is the first term
- ( a_n ) is the ( n )th term

Given:

- ( a_1 = 7 )
- ( d = -The sum of an arithmetic sequence can be found using the formula:

[ S_n = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S_n ) is the sum of the first ( n ) terms,
- ( a_1 ) is the first term of the sequence,
- ( a_n ) is the ( n )-th term of the sequence, -The sum ( S ) of an arithmetic sequence can be found using the formula:

[ S = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S ) is the sum of the sequence
- ( n ) is the number of terms
- ( a_1 ) is the first term
- ( a_n ) is the ( n )th term

Given:

- ( a_1 = 7 )
- ( d = -3The sum of an arithmetic sequence can be found using the formula:

[ S_n = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S_n ) is the sum of the first ( n ) terms,
- ( a_1 ) is the first term of the sequence,
- ( a_n ) is the ( n )-th term of the sequence,
- (The sum ( S ) of an arithmetic sequence can be found using the formula:

[ S = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S ) is the sum of the sequence
- ( n ) is the number of terms
- ( a_1 ) is the first term
- ( a_n ) is the ( n )th term

Given:

- ( a_1 = 7 )
- ( d = -3 ) (common difference)
- ( n = 20 )

First,The sum of an arithmetic sequence can be found using the formula:

[ S_n = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S_n ) is the sum of the first ( n ) terms,
- ( a_1 ) is the first term of the sequence,
- ( a_n ) is the ( n )-th term of the sequence,
- ( nThe sum ( S ) of an arithmetic sequence can be found using the formula:

[ S = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S ) is the sum of the sequence
- ( n ) is the number of terms
- ( a_1 ) is the first term
- ( a_n ) is the ( n )th term

Given:

- ( a_1 = 7 )
- ( d = -3 ) (common difference)
- ( n = 20 )

First, weThe sum of an arithmetic sequence can be found using the formula:

[ S_n = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S_n ) is the sum of the first ( n ) terms,
- ( a_1 ) is the first term of the sequence,
- ( a_n ) is the ( n )-th term of the sequence,
- ( n \The sum ( S ) of an arithmetic sequence can be found using the formula:

[ S = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S ) is the sum of the sequence
- ( n ) is the number of terms
- ( a_1 ) is the first term
- ( a_n ) is the ( n )th term

Given:

- ( a_1 = 7 )
- ( d = -3 ) (common difference)
- ( n = 20 )

First, we needThe sum of an arithmetic sequence can be found using the formula:

[ S_n = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S_n ) is the sum of the first ( n ) terms,
- ( a_1 ) is the first term of the sequence,
- ( a_n ) is the ( n )-th term of the sequence,
- ( n ) is the number of terms in the sequence.

Given: ( a_1 =The sum ( S ) of an arithmetic sequence can be found using the formula:

[ S = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S ) is the sum of the sequence
- ( n ) is the number of terms
- ( a_1 ) is the first term
- ( a_n ) is the ( n )th term

Given:

- ( a_1 = 7 )
- ( d = -3 ) (common difference)
- ( n = 20 )

First, we need to find the (The sum of an arithmetic sequence can be found using the formula:

[ S_n = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S_n ) is the sum of the first ( n ) terms,
- ( a_1 ) is the first term of the sequence,
- ( a_n ) is the ( n )-th term of the sequence,
- ( n ) is the number of terms in the sequence.

Given: ( a_1 = The sum ( S ) of an arithmetic sequence can be found using the formula:

[ S = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S ) is the sum of the sequence
- ( n ) is the number of terms
- ( a_1 ) is the first term
- ( a_n ) is the ( n )th term

Given:

- ( a_1 = 7 )
- ( d = -3 ) (common difference)
- ( n = 20 )

First, we need to find the ( n \The sum of an arithmetic sequence can be found using the formula:

[ S_n = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S_n ) is the sum of the first ( n ) terms,
- ( a_1 ) is the first term of the sequence,
- ( a_n ) is the ( n )-th term of the sequence,
- ( n ) is the number of terms in the sequence.

Given: ( a_1 = 7The sum ( S ) of an arithmetic sequence can be found using the formula:

[ S = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S ) is the sum of the sequence
- ( n ) is the number of terms
- ( a_1 ) is the first term
- ( a_n ) is the ( n )th term

Given:

- ( a_1 = 7 )
- ( d = -3 ) (common difference)
- ( n = 20 )

First, we need to find the ( n )The sum of an arithmetic sequence can be found using the formula:

[ S_n = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S_n ) is the sum of the first ( n ) terms,
- ( a_1 ) is the first term of the sequence,
- ( a_n ) is the ( n )-th term of the sequence,
- ( n ) is the number of terms in the sequence.

Given: ( a_1 = 7 ) (The sum ( S ) of an arithmetic sequence can be found using the formula:

[ S = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S ) is the sum of the sequence
- ( n ) is the number of terms
- ( a_1 ) is the first term
- ( a_n ) is the ( n )th term

Given:

- ( a_1 = 7 )
- ( d = -3 ) (common difference)
- ( n = 20 )

First, we need to find the ( n )thThe sum of an arithmetic sequence can be found using the formula:

[ S_n = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S_n ) is the sum of the first ( n ) terms,
- ( a_1 ) is the first term of the sequence,
- ( a_n ) is the ( n )-th term of the sequence,
- ( n ) is the number of terms in the sequence.

Given: ( a_1 = 7 ) (firstThe sum ( S ) of an arithmetic sequence can be found using the formula:

[ S = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S ) is the sum of the sequence
- ( n ) is the number of terms
- ( a_1 ) is the first term
- ( a_n ) is the ( n )th term

Given:

- ( a_1 = 7 )
- ( d = -3 ) (common difference)
- ( n = 20 )

First, we need to find the ( n )th term (The sum of an arithmetic sequence can be found using the formula:

[ S_n = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S_n ) is the sum of the first ( n ) terms,
- ( a_1 ) is the first term of the sequence,
- ( a_n ) is the ( n )-th term of the sequence,
- ( n ) is the number of terms in the sequence.

Given: ( a_1 = 7 ) (first termThe sum ( S ) of an arithmetic sequence can be found using the formula:

[ S = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S ) is the sum of the sequence
- ( n ) is the number of terms
- ( a_1 ) is the first term
- ( a_n ) is the ( n )th term

Given:

- ( a_1 = 7 )
- ( d = -3 ) (common difference)
- ( n = 20 )

First, we need to find the ( n )th term ( aThe sum of an arithmetic sequence can be found using the formula:

[ S_n = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S_n ) is the sum of the first ( n ) terms,
- ( a_1 ) is the first term of the sequence,
- ( a_n ) is the ( n )-th term of the sequence,
- ( n ) is the number of terms in the sequence.

Given: ( a_1 = 7 ) (first term) (The sum ( S ) of an arithmetic sequence can be found using the formula:

[ S = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S ) is the sum of the sequence
- ( n ) is the number of terms
- ( a_1 ) is the first term
- ( a_n ) is the ( n )th term

Given:

- ( a_1 = 7 )
- ( d = -3 ) (common difference)
- ( n = 20 )

First, we need to find the ( n )th term ( a_nThe sum of an arithmetic sequence can be found using the formula:

[ S_n = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S_n ) is the sum of the first ( n ) terms,
- ( a_1 ) is the first term of the sequence,
- ( a_n ) is the ( n )-th term of the sequence,
- ( n ) is the number of terms in the sequence.

Given: ( a_1 = 7 ) (first term) ( dThe sum ( S ) of an arithmetic sequence can be found using the formula:

[ S = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S ) is the sum of the sequence
- ( n ) is the number of terms
- ( a_1 ) is the first term
- ( a_n ) is the ( n )th term

Given:

- ( a_1 = 7 )
- ( d = -3 ) (common difference)
- ( n = 20 )

First, we need to find the ( n )th term ( a_n \The sum of an arithmetic sequence can be found using the formula:

[ S_n = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S_n ) is the sum of the first ( n ) terms,
- ( a_1 ) is the first term of the sequence,
- ( a_n ) is the ( n )-th term of the sequence,
- ( n ) is the number of terms in the sequence.

Given: ( a_1 = 7 ) (first term) ( d =The sum ( S ) of an arithmetic sequence can be found using the formula:

[ S = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S ) is the sum of the sequence
- ( n ) is the number of terms
- ( a_1 ) is the first term
- ( a_n ) is the ( n )th term

Given:

- ( a_1 = 7 )
- ( d = -3 ) (common difference)
- ( n = 20 )

First, we need to find the ( n )th term ( a_n ) usingThe sum of an arithmetic sequence can be found using the formula:

[ S_n = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S_n ) is the sum of the first ( n ) terms,
- ( a_1 ) is the first term of the sequence,
- ( a_n ) is the ( n )-th term of the sequence,
- ( n ) is the number of terms in the sequence.

Given: ( a_1 = 7 ) (first term) ( d = -3The sum ( S ) of an arithmetic sequence can be found using the formula:

[ S = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S ) is the sum of the sequence
- ( n ) is the number of terms
- ( a_1 ) is the first term
- ( a_n ) is the ( n )th term

Given:

- ( a_1 = 7 )
- ( d = -3 ) (common difference)
- ( n = 20 )

First, we need to find the ( n )th term ( a_n ) using theThe sum of an arithmetic sequence can be found using the formula:

[ S_n = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S_n ) is the sum of the first ( n ) terms,
- ( a_1 ) is the first term of the sequence,
- ( a_n ) is the ( n )-th term of the sequence,
- ( n ) is the number of terms in the sequence.

Given: ( a_1 = 7 ) (first term) ( d = -3 \The sum ( S ) of an arithmetic sequence can be found using the formula:

[ S = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S ) is the sum of the sequence
- ( n ) is the number of terms
- ( a_1 ) is the first term
- ( a_n ) is the ( n )th term

Given:

- ( a_1 = 7 )
- ( d = -3 ) (common difference)
- ( n = 20 )

First, we need to find the ( n )th term ( a_n ) using the formulaThe sum of an arithmetic sequence can be found using the formula:

[ S_n = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S_n ) is the sum of the first ( n ) terms,
- ( a_1 ) is the first term of the sequence,
- ( a_n ) is the ( n )-th term of the sequence,
- ( n ) is the number of terms in the sequence.

Given: ( a_1 = 7 ) (first term) ( d = -3 )The sum ( S ) of an arithmetic sequence can be found using the formula:

[ S = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S ) is the sum of the sequence
- ( n ) is the number of terms
- ( a_1 ) is the first term
- ( a_n ) is the ( n )th term

Given:

- ( a_1 = 7 )
- ( d = -3 ) (common difference)
- ( n = 20 )

First, we need to find the ( n )th term ( a_n ) using the formula for theThe sum of an arithmetic sequence can be found using the formula:

[ S_n = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S_n ) is the sum of the first ( n ) terms,
- ( a_1 ) is the first term of the sequence,
- ( a_n ) is the ( n )-th term of the sequence,
- ( n ) is the number of terms in the sequence.

Given: ( a_1 = 7 ) (first term) ( d = -3 ) (The sum ( S ) of an arithmetic sequence can be found using the formula:

[ S = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S ) is the sum of the sequence
- ( n ) is the number of terms
- ( a_1 ) is the first term
- ( a_n ) is the ( n )th term

Given:

- ( a_1 = 7 )
- ( d = -3 ) (common difference)
- ( n = 20 )

First, we need to find the ( n )th term ( a_n ) using the formula for the ( nThe sum of an arithmetic sequence can be found using the formula:

[ S_n = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S_n ) is the sum of the first ( n ) terms,
- ( a_1 ) is the first term of the sequence,
- ( a_n ) is the ( n )-th term of the sequence,
- ( n ) is the number of terms in the sequence.

Given: ( a_1 = 7 ) (first term) ( d = -3 ) (commonThe sum ( S ) of an arithmetic sequence can be found using the formula:

[ S = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S ) is the sum of the sequence
- ( n ) is the number of terms
- ( a_1 ) is the first term
- ( a_n ) is the ( n )th term

Given:

- ( a_1 = 7 )
- ( d = -3 ) (common difference)
- ( n = 20 )

First, we need to find the ( n )th term ( a_n ) using the formula for the ( n )The sum of an arithmetic sequence can be found using the formula:

[ S_n = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S_n ) is the sum of the first ( n ) terms,
- ( a_1 ) is the first term of the sequence,
- ( a_n ) is the ( n )-th term of the sequence,
- ( n ) is the number of terms in the sequence.

Given: ( a_1 = 7 ) (first term) ( d = -3 ) (common difference) (The sum ( S ) of an arithmetic sequence can be found using the formula:

[ S = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S ) is the sum of the sequence
- ( n ) is the number of terms
- ( a_1 ) is the first term
- ( a_n ) is the ( n )th term

Given:

- ( a_1 = 7 )
- ( d = -3 ) (common difference)
- ( n = 20 )

First, we need to find the ( n )th term ( a_n ) using the formula for the ( n )th termThe sum of an arithmetic sequence can be found using the formula:

[ S_n = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S_n ) is the sum of the first ( n ) terms,
- ( a_1 ) is the first term of the sequence,
- ( a_n ) is the ( n )-th term of the sequence,
- ( n ) is the number of terms in the sequence.

Given: ( a_1 = 7 ) (first term) ( d = -3 ) (common difference) ( n =The sum ( S ) of an arithmetic sequence can be found using the formula:

[ S = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S ) is the sum of the sequence
- ( n ) is the number of terms
- ( a_1 ) is the first term
- ( a_n ) is the ( n )th term

Given:

- ( a_1 = 7 )
- ( d = -3 ) (common difference)
- ( n = 20 )

First, we need to find the ( n )th term ( a_n ) using the formula for the ( n )th term of anThe sum of an arithmetic sequence can be found using the formula:

[ S_n = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S_n ) is the sum of the first ( n ) terms,
- ( a_1 ) is the first term of the sequence,
- ( a_n ) is the ( n )-th term of the sequence,
- ( n ) is the number of terms in the sequence.

Given: ( a_1 = 7 ) (first term) ( d = -3 ) (common difference) ( n = The sum ( S ) of an arithmetic sequence can be found using the formula:

[ S = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S ) is the sum of the sequence
- ( n ) is the number of terms
- ( a_1 ) is the first term
- ( a_n ) is the ( n )th term

Given:

- ( a_1 = 7 )
- ( d = -3 ) (common difference)
- ( n = 20 )

First, we need to find the ( n )th term ( a_n ) using the formula for the ( n )th term of an arithmeticThe sum of an arithmetic sequence can be found using the formula:

[ S_n = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S_n ) is the sum of the first ( n ) terms,
- ( a_1 ) is the first term of the sequence,
- ( a_n ) is the ( n )-th term of the sequence,
- ( n ) is the number of terms in the sequence.

Given: ( a_1 = 7 ) (first term) ( d = -3 ) (common difference) ( n = 20The sum ( S ) of an arithmetic sequence can be found using the formula:

[ S = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S ) is the sum of the sequence
- ( n ) is the number of terms
- ( a_1 ) is the first term
- ( a_n ) is the ( n )th term

Given:

- ( a_1 = 7 )
- ( d = -3 ) (common difference)
- ( n = 20 )

First, we need to find the ( n )th term ( a_n ) using the formula for the ( n )th term of an arithmetic sequenceThe sum of an arithmetic sequence can be found using the formula:

[ S_n = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S_n ) is the sum of the first ( n ) terms,
- ( a_1 ) is the first term of the sequence,
- ( a_n ) is the ( n )-th term of the sequence,
- ( n ) is the number of terms in the sequence.

Given: ( a_1 = 7 ) (first term) ( d = -3 ) (common difference) ( n = 20 \The sum ( S ) of an arithmetic sequence can be found using the formula:

[ S = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S ) is the sum of the sequence
- ( n ) is the number of terms
- ( a_1 ) is the first term
- ( a_n ) is the ( n )th term

Given:

- ( a_1 = 7 )
- ( d = -3 ) (common difference)
- ( n = 20 )

First, we need to find the ( n )th term ( a_n ) using the formula for the ( n )th term of an arithmetic sequence:

The sum of an arithmetic sequence can be found using the formula:

[ S_n = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S_n ) is the sum of the first ( n ) terms,
- ( a_1 ) is the first term of the sequence,
- ( a_n ) is the ( n )-th term of the sequence,
- ( n ) is the number of terms in the sequence.

Given: ( a_1 = 7 ) (first term) ( d = -3 ) (common difference) ( n = 20 )The sum ( S ) of an arithmetic sequence can be found using the formula:

[ S = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S ) is the sum of the sequence
- ( n ) is the number of terms
- ( a_1 ) is the first term
- ( a_n ) is the ( n )th term

Given:

- ( a_1 = 7 )
- ( d = -3 ) (common difference)
- ( n = 20 )

First, we need to find the ( n )th term ( a_n ) using the formula for the ( n )th term of an arithmetic sequence:

[The sum of an arithmetic sequence can be found using the formula:

[ S_n = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S_n ) is the sum of the first ( n ) terms,
- ( a_1 ) is the first term of the sequence,
- ( a_n ) is the ( n )-th term of the sequence,
- ( n ) is the number of terms in the sequence.

Given: ( a_1 = 7 ) (first term) ( d = -3 ) (common difference) ( n = 20 ) (numberThe sum ( S ) of an arithmetic sequence can be found using the formula:

[ S = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S ) is the sum of the sequence
- ( n ) is the number of terms
- ( a_1 ) is the first term
- ( a_n ) is the ( n )th term

Given:

- ( a_1 = 7 )
- ( d = -3 ) (common difference)
- ( n = 20 )

First, we need to find the ( n )th term ( a_n ) using the formula for the ( n )th term of an arithmetic sequence:

[ a_n =The sum of an arithmetic sequence can be found using the formula:

[ S_n = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S_n ) is the sum of the first ( n ) terms,
- ( a_1 ) is the first term of the sequence,
- ( a_n ) is the ( n )-th term of the sequence,
- ( n ) is the number of terms in the sequence.

Given: ( a_1 = 7 ) (first term) ( d = -3 ) (common difference) ( n = 20 ) (number of termsThe sum ( S ) of an arithmetic sequence can be found using the formula:

[ S = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S ) is the sum of the sequence
- ( n ) is the number of terms
- ( a_1 ) is the first term
- ( a_n ) is the ( n )th term

Given:

- ( a_1 = 7 )
- ( d = -3 ) (common difference)
- ( n = 20 )

[ a_n = aThe sum of an arithmetic sequence can be found using the formula:

[ S_n = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S_n ) is the sum of the first ( n ) terms,
- ( a_1 ) is the first term of the sequence,
- ( a_n ) is the ( n )-th term of the sequence,
- ( n ) is the number of terms in the sequence.

Given: ( a_1 = 7 ) (first term) ( d = -3 ) (common difference) ( n = 20 ) (number of terms)

The sum ( S ) of an arithmetic sequence can be found using the formula:

[ S = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S ) is the sum of the sequence
- ( n ) is the number of terms
- ( a_1 ) is the first term
- ( a_n ) is the ( n )th term

Given:

- ( a_1 = 7 )
- ( d = -3 ) (common difference)
- ( n = 20 )

[ a_n = a_The sum of an arithmetic sequence can be found using the formula:

[ S_n = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S_n ) is the sum of the first ( n ) terms,
- ( a_1 ) is the first term of the sequence,
- ( a_n ) is the ( n )-th term of the sequence,
- ( n ) is the number of terms in the sequence.

Given: ( a_1 = 7 ) (first term) ( d = -3 ) (common difference) ( n = 20 ) (number of terms)

FirstThe sum ( S ) of an arithmetic sequence can be found using the formula:

[ S = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S ) is the sum of the sequence
- ( n ) is the number of terms
- ( a_1 ) is the first term
- ( a_n ) is the ( n )th term

Given:

- ( a_1 = 7 )
- ( d = -3 ) (common difference)
- ( n = 20 )

[ a_n = a_1The sum of an arithmetic sequence can be found using the formula:

[ S_n = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S_n ) is the sum of the first ( n ) terms,
- ( a_1 ) is the first term of the sequence,
- ( a_n ) is the ( n )-th term of the sequence,
- ( n ) is the number of terms in the sequence.

Given: ( a_1 = 7 ) (first term) ( d = -3 ) (common difference) ( n = 20 ) (number of terms)

First,The sum ( S ) of an arithmetic sequence can be found using the formula:

[ S = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S ) is the sum of the sequence
- ( n ) is the number of terms
- ( a_1 ) is the first term
- ( a_n ) is the ( n )th term

Given:

- ( a_1 = 7 )
- ( d = -3 ) (common difference)
- ( n = 20 )

[ a_n = a_1 + (The sum of an arithmetic sequence can be found using the formula:

[ S_n = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S_n ) is the sum of the first ( n ) terms,
- ( a_1 ) is the first term of the sequence,
- ( a_n ) is the ( n )-th term of the sequence,
- ( n ) is the number of terms in the sequence.

Given: ( a_1 = 7 ) (first term) ( d = -3 ) (common difference) ( n = 20 ) (number of terms)

First, findThe sum ( S ) of an arithmetic sequence can be found using the formula:

[ S = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S ) is the sum of the sequence
- ( n ) is the number of terms
- ( a_1 ) is the first term
- ( a_n ) is the ( n )th term

Given:

- ( a_1 = 7 )
- ( d = -3 ) (common difference)
- ( n = 20 )

[ a_n = a_1 + (nThe sum of an arithmetic sequence can be found using the formula:

[ S_n = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S_n ) is the sum of the first ( n ) terms,
- ( a_1 ) is the first term of the sequence,
- ( a_n ) is the ( n )-th term of the sequence,
- ( n ) is the number of terms in the sequence.

Given: ( a_1 = 7 ) (first term) ( d = -3 ) (common difference) ( n = 20 ) (number of terms)

First, find theThe sum ( S ) of an arithmetic sequence can be found using the formula:

[ S = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S ) is the sum of the sequence
- ( n ) is the number of terms
- ( a_1 ) is the first term
- ( a_n ) is the ( n )th term

Given:

- ( a_1 = 7 )
- ( d = -3 ) (common difference)
- ( n = 20 )

[ a_n = a_1 + (n -The sum of an arithmetic sequence can be found using the formula:

[ S_n = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S_n ) is the sum of the first ( n ) terms,
- ( a_1 ) is the first term of the sequence,
- ( a_n ) is the ( n )-th term of the sequence,
- ( n ) is the number of terms in the sequence.

Given: ( a_1 = 7 ) (first term) ( d = -3 ) (common difference) ( n = 20 ) (number of terms)

First, find the (The sum ( S ) of an arithmetic sequence can be found using the formula:

[ S = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S ) is the sum of the sequence
- ( n ) is the number of terms
- ( a_1 ) is the first term
- ( a_n ) is the ( n )th term

Given:

- ( a_1 = 7 )
- ( d = -3 ) (common difference)
- ( n = 20 )

[ a_n = a_1 + (n - The sum of an arithmetic sequence can be found using the formula:

[ S_n = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S_n ) is the sum of the first ( n ) terms,
- ( a_1 ) is the first term of the sequence,
- ( a_n ) is the ( n )-th term of the sequence,
- ( n ) is the number of terms in the sequence.

Given: ( a_1 = 7 ) (first term) ( d = -3 ) (common difference) ( n = 20 ) (number of terms)

First, find the ( nThe sum ( S ) of an arithmetic sequence can be found using the formula:

[ S = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S ) is the sum of the sequence
- ( n ) is the number of terms
- ( a_1 ) is the first term
- ( a_n ) is the ( n )th term

Given:

- ( a_1 = 7 )
- ( d = -3 ) (common difference)
- ( n = 20 )

[ a_n = a_1 + (n - 1The sum of an arithmetic sequence can be found using the formula:

[ S_n = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S_n ) is the sum of the first ( n ) terms,
- ( a_1 ) is the first term of the sequence,
- ( a_n ) is the ( n )-th term of the sequence,
- ( n ) is the number of terms in the sequence.

Given: ( a_1 = 7 ) (first term) ( d = -3 ) (common difference) ( n = 20 ) (number of terms)

First, find the ( n \The sum ( S ) of an arithmetic sequence can be found using the formula:

[ S = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S ) is the sum of the sequence
- ( n ) is the number of terms
- ( a_1 ) is the first term
- ( a_n ) is the ( n )th term

Given:

- ( a_1 = 7 )
- ( d = -3 ) (common difference)
- ( n = 20 )

[ a_n = a_1 + (n - 1)dThe sum of an arithmetic sequence can be found using the formula:

[ S_n = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S_n ) is the sum of the first ( n ) terms,
- ( a_1 ) is the first term of the sequence,
- ( a_n ) is the ( n )-th term of the sequence,
- ( n ) is the number of terms in the sequence.

Given: ( a_1 = 7 ) (first term) ( d = -3 ) (common difference) ( n = 20 ) (number of terms)

First, find the ( n )-The sum ( S ) of an arithmetic sequence can be found using the formula:

[ S = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S ) is the sum of the sequence
- ( n ) is the number of terms
- ( a_1 ) is the first term
- ( a_n ) is the ( n )th term

Given:

- ( a_1 = 7 )
- ( d = -3 ) (common difference)
- ( n = 20 )

[ a_n = a_1 + (n - 1)d \The sum of an arithmetic sequence can be found using the formula:

[ S_n = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S_n ) is the sum of the first ( n ) terms,
- ( a_1 ) is the first term of the sequence,
- ( a_n ) is the ( n )-th term of the sequence,
- ( n ) is the number of terms in the sequence.

Given: ( a_1 = 7 ) (first term) ( d = -3 ) (common difference) ( n = 20 ) (number of terms)

First, find the ( n )-thThe sum ( S ) of an arithmetic sequence can be found using the formula:

[ S = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S ) is the sum of the sequence
- ( n ) is the number of terms
- ( a_1 ) is the first term
- ( a_n ) is the ( n )th term

Given:

- ( a_1 = 7 )
- ( d = -3 ) (common difference)
- ( n = 20 )

[ a_n = a_1 + (n - 1)d ]

The sum of an arithmetic sequence can be found using the formula:

[ S_n = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S_n ) is the sum of the first ( n ) terms,
- ( a_1 ) is the first term of the sequence,
- ( a_n ) is the ( n )-th term of the sequence,
- ( n ) is the number of terms in the sequence.

Given: ( a_1 = 7 ) (first term) ( d = -3 ) (common difference) ( n = 20 ) (number of terms)

First, find the ( n )-th termThe sum ( S ) of an arithmetic sequence can be found using the formula:

[ S = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S ) is the sum of the sequence
- ( n ) is the number of terms
- ( a_1 ) is the first term
- ( a_n ) is the ( n )th term

Given:

- ( a_1 = 7 )
- ( d = -3 ) (common difference)
- ( n = 20 )

[ a_n = a_1 + (n - 1)d ]

SubThe sum of an arithmetic sequence can be found using the formula:

[ S_n = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S_n ) is the sum of the first ( n ) terms,
- ( a_1 ) is the first term of the sequence,
- ( a_n ) is the ( n )-th term of the sequence,
- ( n ) is the number of terms in the sequence.

Given: ( a_1 = 7 ) (first term) ( d = -3 ) (common difference) ( n = 20 ) (number of terms)

First, find the ( n )-th term (The sum ( S ) of an arithmetic sequence can be found using the formula:

[ S = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S ) is the sum of the sequence
- ( n ) is the number of terms
- ( a_1 ) is the first term
- ( a_n ) is the ( n )th term

Given:

- ( a_1 = 7 )
- ( d = -3 ) (common difference)
- ( n = 20 )

[ a_n = a_1 + (n - 1)d ]

SubstituteThe sum of an arithmetic sequence can be found using the formula:

[ S_n = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S_n ) is the sum of the first ( n ) terms,
- ( a_1 ) is the first term of the sequence,
- ( a_n ) is the ( n )-th term of the sequence,
- ( n ) is the number of terms in the sequence.

Given: ( a_1 = 7 ) (first term) ( d = -3 ) (common difference) ( n = 20 ) (number of terms)

First, find the ( n )-th term ( aThe sum ( S ) of an arithmetic sequence can be found using the formula:

[ S = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S ) is the sum of the sequence
- ( n ) is the number of terms
- ( a_1 ) is the first term
- ( a_n ) is the ( n )th term

Given:

- ( a_1 = 7 )
- ( d = -3 ) (common difference)
- ( n = 20 )

[ a_n = a_1 + (n - 1)d ]

Substitute theThe sum of an arithmetic sequence can be found using the formula:

[ S_n = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S_n ) is the sum of the first ( n ) terms,
- ( a_1 ) is the first term of the sequence,
- ( a_n ) is the ( n )-th term of the sequence,
- ( n ) is the number of terms in the sequence.

Given: ( a_1 = 7 ) (first term) ( d = -3 ) (common difference) ( n = 20 ) (number of terms)

First, find the ( n )-th term ( a_nThe sum ( S ) of an arithmetic sequence can be found using the formula:

[ S = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S ) is the sum of the sequence
- ( n ) is the number of terms
- ( a_1 ) is the first term
- ( a_n ) is the ( n )th term

Given:

- ( a_1 = 7 )
- ( d = -3 ) (common difference)
- ( n = 20 )

[ a_n = a_1 + (n - 1)d ]

Substitute the given valuesThe sum of an arithmetic sequence can be found using the formula:

[ S_n = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S_n ) is the sum of the first ( n ) terms,
- ( a_1 ) is the first term of the sequence,
- ( a_n ) is the ( n )-th term of the sequence,
- ( n ) is the number of terms in the sequence.

Given: ( a_1 = 7 ) (first term) ( d = -3 ) (common difference) ( n = 20 ) (number of terms)

First, find the ( n )-th term ( a_n \The sum ( S ) of an arithmetic sequence can be found using the formula:

[ S = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S ) is the sum of the sequence
- ( n ) is the number of terms
- ( a_1 ) is the first term
- ( a_n ) is the ( n )th term

Given:

- ( a_1 = 7 )
- ( d = -3 ) (common difference)
- ( n = 20 )

[ a_n = a_1 + (n - 1)d ]

Substitute the given values:

The sum of an arithmetic sequence can be found using the formula:

[ S_n = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S_n ) is the sum of the first ( n ) terms,
- ( a_1 ) is the first term of the sequence,
- ( a_n ) is the ( n )-th term of the sequence,
- ( n ) is the number of terms in the sequence.

Given: ( a_1 = 7 ) (first term) ( d = -3 ) (common difference) ( n = 20 ) (number of terms)

First, find the ( n )-th term ( a_n )The sum ( S ) of an arithmetic sequence can be found using the formula:

[ S = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S ) is the sum of the sequence
- ( n ) is the number of terms
- ( a_1 ) is the first term
- ( a_n ) is the ( n )th term

Given:

- ( a_1 = 7 )
- ( d = -3 ) (common difference)
- ( n = 20 )

[ a_n = a_1 + (n - 1)d ]

Substitute the given values:

[ aThe sum of an arithmetic sequence can be found using the formula:

[ S_n = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S_n ) is the sum of the first ( n ) terms,
- ( a_1 ) is the first term of the sequence,
- ( a_n ) is the ( n )-th term of the sequence,
- ( n ) is the number of terms in the sequence.

Given: ( a_1 = 7 ) (first term) ( d = -3 ) (common difference) ( n = 20 ) (number of terms)

First, find the ( n )-th term ( a_n ) using theThe sum ( S ) of an arithmetic sequence can be found using the formula:

[ S = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S ) is the sum of the sequence
- ( n ) is the number of terms
- ( a_1 ) is the first term
- ( a_n ) is the ( n )th term

Given:

- ( a_1 = 7 )
- ( d = -3 ) (common difference)
- ( n = 20 )

[ a_n = a_1 + (n - 1)d ]

Substitute the given values:

[ a_nThe sum of an arithmetic sequence can be found using the formula:

[ S_n = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S_n ) is the sum of the first ( n ) terms,
- ( a_1 ) is the first term of the sequence,
- ( a_n ) is the ( n )-th term of the sequence,
- ( n ) is the number of terms in the sequence.

Given: ( a_1 = 7 ) (first term) ( d = -3 ) (common difference) ( n = 20 ) (number of terms)

First, find the ( n )-th term ( a_n ) using the formula forThe sum ( S ) of an arithmetic sequence can be found using the formula:

[ S = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S ) is the sum of the sequence
- ( n ) is the number of terms
- ( a_1 ) is the first term
- ( a_n ) is the ( n )th term

Given:

- ( a_1 = 7 )
- ( d = -3 ) (common difference)
- ( n = 20 )

[ a_n = a_1 + (n - 1)d ]

Substitute the given values:

[ a_n = The sum of an arithmetic sequence can be found using the formula:

[ S_n = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S_n ) is the sum of the first ( n ) terms,
- ( a_1 ) is the first term of the sequence,
- ( a_n ) is the ( n )-th term of the sequence,
- ( n ) is the number of terms in the sequence.

Given: ( a_1 = 7 ) (first term) ( d = -3 ) (common difference) ( n = 20 ) (number of terms)

First, find the ( n )-th term ( a_n ) using the formula for theThe sum ( S ) of an arithmetic sequence can be found using the formula:

[ S = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S ) is the sum of the sequence
- ( n ) is the number of terms
- ( a_1 ) is the first term
- ( a_n ) is the ( n )th term

Given:

- ( a_1 = 7 )
- ( d = -3 ) (common difference)
- ( n = 20 )

[ a_n = a_1 + (n - 1)d ]

Substitute the given values:

[ a_n = 7 +The sum of an arithmetic sequence can be found using the formula:

[ S_n = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S_n ) is the sum of the first ( n ) terms,
- ( a_1 ) is the first term of the sequence,
- ( a_n ) is the ( n )-th term of the sequence,
- ( n ) is the number of terms in the sequence.

Given: ( a_1 = 7 ) (first term) ( d = -3 ) (common difference) ( n = 20 ) (number of terms)

First, find the ( n )-th term ( a_n ) using the formula for the ( nThe sum ( S ) of an arithmetic sequence can be found using the formula:

[ S = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S ) is the sum of the sequence
- ( n ) is the number of terms
- ( a_1 ) is the first term
- ( a_n ) is the ( n )th term

Given:

- ( a_1 = 7 )
- ( d = -3 ) (common difference)
- ( n = 20 )

[ a_n = a_1 + (n - 1)d ]

Substitute the given values:

[ a_n = 7 + (The sum of an arithmetic sequence can be found using the formula:

[ S_n = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S_n ) is the sum of the first ( n ) terms,
- ( a_1 ) is the first term of the sequence,
- ( a_n ) is the ( n )-th term of the sequence,
- ( n ) is the number of terms in the sequence.

Given: ( a_1 = 7 ) (first term) ( d = -3 ) (common difference) ( n = 20 ) (number of terms)

First, find the ( n )-th term ( a_n ) using the formula for the ( n \The sum ( S ) of an arithmetic sequence can be found using the formula:

[ S = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S ) is the sum of the sequence
- ( n ) is the number of terms
- ( a_1 ) is the first term
- ( a_n ) is the ( n )th term

Given:

- ( a_1 = 7 )
- ( d = -3 ) (common difference)
- ( n = 20 )

[ a_n = a_1 + (n - 1)d ]

Substitute the given values:

[ a_n = 7 + (20 -The sum of an arithmetic sequence can be found using the formula:

[ S_n = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S_n ) is the sum of the first ( n ) terms,
- ( a_1 ) is the first term of the sequence,
- ( a_n ) is the ( n )-th term of the sequence,
- ( n ) is the number of terms in the sequence.

Given: ( a_1 = 7 ) (first term) ( d = -3 ) (common difference) ( n = 20 ) (number of terms)

First, find the ( n )-th term ( a_n ) using the formula for the ( n )-The sum ( S ) of an arithmetic sequence can be found using the formula:

[ S = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S ) is the sum of the sequence
- ( n ) is the number of terms
- ( a_1 ) is the first term
- ( a_n ) is the ( n )th term

Given:

- ( a_1 = 7 )
- ( d = -3 ) (common difference)
- ( n = 20 )

[ a_n = a_1 + (n - 1)d ]

Substitute the given values:

[ a_n = 7 + (20 - The sum of an arithmetic sequence can be found using the formula:

[ S_n = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S_n ) is the sum of the first ( n ) terms,
- ( a_1 ) is the first term of the sequence,
- ( a_n ) is the ( n )-th term of the sequence,
- ( n ) is the number of terms in the sequence.

Given: ( a_1 = 7 ) (first term) ( d = -3 ) (common difference) ( n = 20 ) (number of terms)

First, find the ( n )-th term ( a_n ) using the formula for the ( n )-thThe sum ( S ) of an arithmetic sequence can be found using the formula:

[ S = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S ) is the sum of the sequence
- ( n ) is the number of terms
- ( a_1 ) is the first term
- ( a_n ) is the ( n )th term

Given:

- ( a_1 = 7 )
- ( d = -3 ) (common difference)
- ( n = 20 )

[ a_n = a_1 + (n - 1)d ]

Substitute the given values:

[ a_n = 7 + (20 - 1)(The sum of an arithmetic sequence can be found using the formula:

[ S_n = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S_n ) is the sum of the first ( n ) terms,
- ( a_1 ) is the first term of the sequence,
- ( a_n ) is the ( n )-th term of the sequence,
- ( n ) is the number of terms in the sequence.

Given: ( a_1 = 7 ) (first term) ( d = -3 ) (common difference) ( n = 20 ) (number of terms)

First, find the ( n )-th term ( a_n ) using the formula for the ( n )-th term ofThe sum ( S ) of an arithmetic sequence can be found using the formula:

[ S = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S ) is the sum of the sequence
- ( n ) is the number of terms
- ( a_1 ) is the first term
- ( a_n ) is the ( n )th term

Given:

- ( a_1 = 7 )
- ( d = -3 ) (common difference)
- ( n = 20 )

[ a_n = a_1 + (n - 1)d ]

Substitute the given values:

[ a_n = 7 + (20 - 1)(-3The sum of an arithmetic sequence can be found using the formula:

[ S_n = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S_n ) is the sum of the first ( n ) terms,
- ( a_1 ) is the first term of the sequence,
- ( a_n ) is the ( n )-th term of the sequence,
- ( n ) is the number of terms in the sequence.

Given: ( a_1 = 7 ) (first term) ( d = -3 ) (common difference) ( n = 20 ) (number of terms)

First, find the ( n )-th term ( a_n ) using the formula for the ( n )-th term of an arithmeticThe sum ( S ) of an arithmetic sequence can be found using the formula:

[ S = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S ) is the sum of the sequence
- ( n ) is the number of terms
- ( a_1 ) is the first term
- ( a_n ) is the ( n )th term

Given:

- ( a_1 = 7 )
- ( d = -3 ) (common difference)
- ( n = 20 )

[ a_n = a_1 + (n - 1)d ]

Substitute the given values:

[ a_n = 7 + (20 - 1)(-3) ]

The sum of an arithmetic sequence can be found using the formula:

[ S_n = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S_n ) is the sum of the first ( n ) terms,
- ( a_1 ) is the first term of the sequence,
- ( a_n ) is the ( n )-th term of the sequence,
- ( n ) is the number of terms in the sequence.

Given: ( a_1 = 7 ) (first term) ( d = -3 ) (common difference) ( n = 20 ) (number of terms)

First, find the ( n )-th term ( a_n ) using the formula for the ( n )-th term of an arithmetic sequence:

The sum ( S ) of an arithmetic sequence can be found using the formula:

[ S = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S ) is the sum of the sequence
- ( n ) is the number of terms
- ( a_1 ) is the first term
- ( a_n ) is the ( n )th term

Given:

- ( a_1 = 7 )
- ( d = -3 ) (common difference)
- ( n = 20 )

[ a_n = a_1 + (n - 1)d ]

Substitute the given values:

[ a_n = 7 + (20 - 1)(-3) ]

[ aThe sum of an arithmetic sequence can be found using the formula:

[ S_n = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S_n ) is the sum of the first ( n ) terms,
- ( a_1 ) is the first term of the sequence,
- ( a_n ) is the ( n )-th term of the sequence,
- ( n ) is the number of terms in the sequence.

Given: ( a_1 = 7 ) (first term) ( d = -3 ) (common difference) ( n = 20 ) (number of terms)

First, find the ( n )-th term ( a_n ) using the formula for the ( n )-th term of an arithmetic sequence:

[ aThe sum ( S ) of an arithmetic sequence can be found using the formula:

[ S = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S ) is the sum of the sequence
- ( n ) is the number of terms
- ( a_1 ) is the first term
- ( a_n ) is the ( n )th term

Given:

- ( a_1 = 7 )
- ( d = -3 ) (common difference)
- ( n = 20 )

[ a_n = a_1 + (n - 1)d ]

Substitute the given values:

[ a_n = 7 + (20 - 1)(-3) ]

[ a_nThe sum of an arithmetic sequence can be found using the formula:

[ S_n = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S_n ) is the sum of the first ( n ) terms,
- ( a_1 ) is the first term of the sequence,
- ( a_n ) is the ( n )-th term of the sequence,
- ( n ) is the number of terms in the sequence.

Given: ( a_1 = 7 ) (first term) ( d = -3 ) (common difference) ( n = 20 ) (number of terms)

First, find the ( n )-th term ( a_n ) using the formula for the ( n )-th term of an arithmetic sequence:

[ a_nThe sum ( S ) of an arithmetic sequence can be found using the formula:

[ S = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S ) is the sum of the sequence
- ( n ) is the number of terms
- ( a_1 ) is the first term
- ( a_n ) is the ( n )th term

Given:

- ( a_1 = 7 )
- ( d = -3 ) (common difference)
- ( n = 20 )

[ a_n = a_1 + (n - 1)d ]

Substitute the given values:

[ a_n = 7 + (20 - 1)(-3) ]

[ a_n =The sum of an arithmetic sequence can be found using the formula:

[ S_n = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S_n ) is the sum of the first ( n ) terms,
- ( a_1 ) is the first term of the sequence,
- ( a_n ) is the ( n )-th term of the sequence,
- ( n ) is the number of terms in the sequence.

Given: ( a_1 = 7 ) (first term) ( d = -3 ) (common difference) ( n = 20 ) (number of terms)

[ a_n =The sum ( S ) of an arithmetic sequence can be found using the formula:

[ S = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S ) is the sum of the sequence
- ( n ) is the number of terms
- ( a_1 ) is the first term
- ( a_n ) is the ( n )th term

Given:

- ( a_1 = 7 )
- ( d = -3 ) (common difference)
- ( n = 20 )

[ a_n = a_1 + (n - 1)d ]

Substitute the given values:

[ a_n = 7 + (20 - 1)(-3) ]

[ a_n = The sum of an arithmetic sequence can be found using the formula:

[ S_n = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S_n ) is the sum of the first ( n ) terms,
- ( a_1 ) is the first term of the sequence,
- ( a_n ) is the ( n )-th term of the sequence,
- ( n ) is the number of terms in the sequence.

Given: ( a_1 = 7 ) (first term) ( d = -3 ) (common difference) ( n = 20 ) (number of terms)

[ a_n = a_1 + (The sum ( S ) of an arithmetic sequence can be found using the formula:

[ S = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S ) is the sum of the sequence
- ( n ) is the number of terms
- ( a_1 ) is the first term
- ( a_n ) is the ( n )th term

Given:

- ( a_1 = 7 )
- ( d = -3 ) (common difference)
- ( n = 20 )

[ a_n = a_1 + (n - 1)d ]

Substitute the given values:

[ a_n = 7 + (20 - 1)(-3) ]

[ a_n = 7The sum of an arithmetic sequence can be found using the formula:

[ S_n = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S_n ) is the sum of the first ( n ) terms,
- ( a_1 ) is the first term of the sequence,
- ( a_n ) is the ( n )-th term of the sequence,
- ( n ) is the number of terms in the sequence.

Given: ( a_1 = 7 ) (first term) ( d = -3 ) (common difference) ( n = 20 ) (number of terms)

[ a_n = a_1 + (nThe sum ( S ) of an arithmetic sequence can be found using the formula:

[ S = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S ) is the sum of the sequence
- ( n ) is the number of terms
- ( a_1 ) is the first term
- ( a_n ) is the ( n )th term

Given:

- ( a_1 = 7 )
- ( d = -3 ) (common difference)
- ( n = 20 )

[ a_n = a_1 + (n - 1)d ]

Substitute the given values:

[ a_n = 7 + (20 - 1)(-3) ]

[ a_n = 7 +The sum of an arithmetic sequence can be found using the formula:

[ S_n = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S_n ) is the sum of the first ( n ) terms,
- ( a_1 ) is the first term of the sequence,
- ( a_n ) is the ( n )-th term of the sequence,
- ( n ) is the number of terms in the sequence.

Given: ( a_1 = 7 ) (first term) ( d = -3 ) (common difference) ( n = 20 ) (number of terms)

[ a_n = a_1 + (n -The sum ( S ) of an arithmetic sequence can be found using the formula:

[ S = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S ) is the sum of the sequence
- ( n ) is the number of terms
- ( a_1 ) is the first term
- ( a_n ) is the ( n )th term

Given:

- ( a_1 = 7 )
- ( d = -3 ) (common difference)
- ( n = 20 )

[ a_n = a_1 + (n - 1)d ]

Substitute the given values:

[ a_n = 7 + (20 - 1)(-3) ]

[ a_n = 7 + 19(-3)The sum of an arithmetic sequence can be found using the formula:

[ S_n = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S_n ) is the sum of the first ( n ) terms,
- ( a_1 ) is the first term of the sequence,
- ( a_n ) is the ( n )-th term of the sequence,
- ( n ) is the number of terms in the sequence.

Given: ( a_1 = 7 ) (first term) ( d = -3 ) (common difference) ( n = 20 ) (number of terms)

[ a_n = a_1 + (n - The sum ( S ) of an arithmetic sequence can be found using the formula:

[ S = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S ) is the sum of the sequence
- ( n ) is the number of terms
- ( a_1 ) is the first term
- ( a_n ) is the ( n )th term

Given:

- ( a_1 = 7 )
- ( d = -3 ) (common difference)
- ( n = 20 )

[ a_n = a_1 + (n - 1)d ]

Substitute the given values:

[ a_n = 7 + (20 - 1)(-3) ]

[ a_n = 7 + 19(-3) ]

The sum of an arithmetic sequence can be found using the formula:

[ S_n = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S_n ) is the sum of the first ( n ) terms,
- ( a_1 ) is the first term of the sequence,
- ( a_n ) is the ( n )-th term of the sequence,
- ( n ) is the number of terms in the sequence.

Given: ( a_1 = 7 ) (first term) ( d = -3 ) (common difference) ( n = 20 ) (number of terms)

[ a_n = a_1 + (n - 1)dThe sum ( S ) of an arithmetic sequence can be found using the formula:

[ S = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S ) is the sum of the sequence
- ( n ) is the number of terms
- ( a_1 ) is the first term
- ( a_n ) is the ( n )th term

Given:

- ( a_1 = 7 )
- ( d = -3 ) (common difference)
- ( n = 20 )

[ a_n = a_1 + (n - 1)d ]

Substitute the given values:

[ a_n = 7 + (20 - 1)(-3) ]

[ a_n = 7 + 19(-3) ]

[The sum of an arithmetic sequence can be found using the formula:

[ S_n = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S_n ) is the sum of the first ( n ) terms,
- ( a_1 ) is the first term of the sequence,
- ( a_n ) is the ( n )-th term of the sequence,
- ( n ) is the number of terms in the sequence.

Given: ( a_1 = 7 ) (first term) ( d = -3 ) (common difference) ( n = 20 ) (number of terms)

[ a_n = a_1 + (n - 1)d ]

[ a_n = 7 + (20 - 1)(-3) ]

[ a_nThe sum ( S ) of an arithmetic sequence can be found using the formula:

[ S = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S ) is the sum of the sequence
- ( n ) is the number of terms
- ( a_1 ) is the first term
- ( a_n ) is the ( n )th term

Given:

- ( a_1 = 7 )
- ( d = -3 ) (common difference)
- ( n = 20 )

[ a_n = a_1 + (n - 1)d ]

Substitute the given values:

[ a_n = 7 + (20 - 1)(-3) ]

[ a_n = 7 + 19(-3) ]

[ aThe sum of an arithmetic sequence can be found using the formula:

[ S_n = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S_n ) is the sum of the first ( n ) terms,
- ( a_1 ) is the first term of the sequence,
- ( a_n ) is the ( n )-th term of the sequence,
- ( n ) is the number of terms in the sequence.

Given: ( a_1 = 7 ) (first term) ( d = -3 ) (common difference) ( n = 20 ) (number of terms)

[ a_n = a_1 + (n - 1)d ]

[ a_n = 7 + (20 - 1)(-3) ]

[ a_n =The sum ( S ) of an arithmetic sequence can be found using the formula:

[ S = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S ) is the sum of the sequence
- ( n ) is the number of terms
- ( a_1 ) is the first term
- ( a_n ) is the ( n )th term

Given:

- ( a_1 = 7 )
- ( d = -3 ) (common difference)
- ( n = 20 )

[ a_n = a_1 + (n - 1)d ]

Substitute the given values:

[ a_n = 7 + (20 - 1)(-3) ]

[ a_n = 7 + 19(-3) ]

[ a_nThe sum of an arithmetic sequence can be found using the formula:

[ S_n = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S_n ) is the sum of the first ( n ) terms,
- ( a_1 ) is the first term of the sequence,
- ( a_n ) is the ( n )-th term of the sequence,
- ( n ) is the number of terms in the sequence.

Given: ( a_1 = 7 ) (first term) ( d = -3 ) (common difference) ( n = 20 ) (number of terms)

[ a_n = a_1 + (n - 1)d ]

[ a_n = 7 + (20 - 1)(-3) ]

[ a_n = The sum ( S ) of an arithmetic sequence can be found using the formula:

[ S = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S ) is the sum of the sequence
- ( n ) is the number of terms
- ( a_1 ) is the first term
- ( a_n ) is the ( n )th term

Given:

- ( a_1 = 7 )
- ( d = -3 ) (common difference)
- ( n = 20 )

[ a_n = a_1 + (n - 1)d ]

Substitute the given values:

[ a_n = 7 + (20 - 1)(-3) ]

[ a_n = 7 + 19(-3) ]

[ a_n = 7 - 57 ]

[ aThe sum of an arithmetic sequence can be found using the formula:

[ S_n = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S_n ) is the sum of the first ( n ) terms,
- ( a_1 ) is the first term of the sequence,
- ( a_n ) is the ( n )-th term of the sequence,
- ( n ) is the number of terms in the sequence.

Given: ( a_1 = 7 ) (first term) ( d = -3 ) (common difference) ( n = 20 ) (number of terms)

[ a_n = a_1 + (n - 1)d ]

[ a_n = 7 + (20 - 1)(-3) ]

[ a_n = 7 +The sum ( S ) of an arithmetic sequence can be found using the formula:

[ S = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S ) is the sum of the sequence
- ( n ) is the number of terms
- ( a_1 ) is the first term
- ( a_n ) is the ( n )th term

Given:

- ( a_1 = 7 )
- ( d = -3 ) (common difference)
- ( n = 20 )

[ a_n = a_1 + (n - 1)d ]

Substitute the given values:

[ a_n = 7 + (20 - 1)(-3) ]

[ a_n = 7 + 19(-3) ]

[ a_n = 7 - 57 ]

[ a_nThe sum of an arithmetic sequence can be found using the formula:

[ S_n = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S_n ) is the sum of the first ( n ) terms,
- ( a_1 ) is the first term of the sequence,
- ( a_n ) is the ( n )-th term of the sequence,
- ( n ) is the number of terms in the sequence.

Given: ( a_1 = 7 ) (first term) ( d = -3 ) (common difference) ( n = 20 ) (number of terms)

[ a_n = a_1 + (n - 1)d ]

[ a_n = 7 + (20 - 1)(-3) ]

[ a_n = 7 + The sum ( S ) of an arithmetic sequence can be found using the formula:

[ S = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S ) is the sum of the sequence
- ( n ) is the number of terms
- ( a_1 ) is the first term
- ( a_n ) is the ( n )th term

Given:

- ( a_1 = 7 )
- ( d = -3 ) (common difference)
- ( n = 20 )

[ a_n = a_1 + (n - 1)d ]

Substitute the given values:

[ a_n = 7 + (20 - 1)(-3) ]

[ a_n = 7 + 19(-3) ]

[ a_n = 7 - 57 ]

[ a_n =The sum of an arithmetic sequence can be found using the formula:

[ S_n = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S_n ) is the sum of the first ( n ) terms,
- ( a_1 ) is the first term of the sequence,
- ( a_n ) is the ( n )-th term of the sequence,
- ( n ) is the number of terms in the sequence.

Given: ( a_1 = 7 ) (first term) ( d = -3 ) (common difference) ( n = 20 ) (number of terms)

[ a_n = a_1 + (n - 1)d ]

[ a_n = 7 + (20 - 1)(-3) ]

[ a_n = 7 + 19The sum ( S ) of an arithmetic sequence can be found using the formula:

[ S = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S ) is the sum of the sequence
- ( n ) is the number of terms
- ( a_1 ) is the first term
- ( a_n ) is the ( n )th term

Given:

- ( a_1 = 7 )
- ( d = -3 ) (common difference)
- ( n = 20 )

[ a_n = a_1 + (n - 1)d ]

Substitute the given values:

[ a_n = 7 + (20 - 1)(-3) ]

[ a_n = 7 + 19(-3) ]

[ a_n = 7 - 57 ]

[ a_n = -50The sum of an arithmetic sequence can be found using the formula:

[ S_n = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S_n ) is the sum of the first ( n ) terms,
- ( a_1 ) is the first term of the sequence,
- ( a_n ) is the ( n )-th term of the sequence,
- ( n ) is the number of terms in the sequence.

Given: ( a_1 = 7 ) (first term) ( d = -3 ) (common difference) ( n = 20 ) (number of terms)

[ a_n = a_1 + (n - 1)d ]

[ a_n = 7 + (20 - 1)(-3) ]

[ a_n = 7 + 19(-The sum ( S ) of an arithmetic sequence can be found using the formula:

[ S = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S ) is the sum of the sequence
- ( n ) is the number of terms
- ( a_1 ) is the first term
- ( a_n ) is the ( n )th term

Given:

- ( a_1 = 7 )
- ( d = -3 ) (common difference)
- ( n = 20 )

[ a_n = a_1 + (n - 1)d ]

Substitute the given values:

[ a_n = 7 + (20 - 1)(-3) ]

[ a_n = 7 + 19(-3) ]

[ a_n = 7 - 57 ]

[ a_n = -50 \The sum of an arithmetic sequence can be found using the formula:

[ S_n = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S_n ) is the sum of the first ( n ) terms,
- ( a_1 ) is the first term of the sequence,
- ( a_n ) is the ( n )-th term of the sequence,
- ( n ) is the number of terms in the sequence.

Given: ( a_1 = 7 ) (first term) ( d = -3 ) (common difference) ( n = 20 ) (number of terms)

[ a_n = a_1 + (n - 1)d ]

[ a_n = 7 + (20 - 1)(-3) ]

[ a_n = 7 + 19(-3The sum ( S ) of an arithmetic sequence can be found using the formula:

[ S = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S ) is the sum of the sequence
- ( n ) is the number of terms
- ( a_1 ) is the first term
- ( a_n ) is the ( n )th term

Given:

- ( a_1 = 7 )
- ( d = -3 ) (common difference)
- ( n = 20 )

[ a_n = a_1 + (n - 1)d ]

Substitute the given values:

[ a_n = 7 + (20 - 1)(-3) ]

[ a_n = 7 + 19(-3) ]

[ a_n = 7 - 57 ]

[ a_n = -50 ]

The sum of an arithmetic sequence can be found using the formula:

[ S_n = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S_n ) is the sum of the first ( n ) terms,
- ( a_1 ) is the first term of the sequence,
- ( a_n ) is the ( n )-th term of the sequence,
- ( n ) is the number of terms in the sequence.

Given: ( a_1 = 7 ) (first term) ( d = -3 ) (common difference) ( n = 20 ) (number of terms)

[ a_n = a_1 + (n - 1)d ]

[ a_n = 7 + (20 - 1)(-3) ]

[ a_n = 7 + 19(-3)The sum ( S ) of an arithmetic sequence can be found using the formula:

[ S = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S ) is the sum of the sequence
- ( n ) is the number of terms
- ( a_1 ) is the first term
- ( a_n ) is the ( n )th term

Given:

- ( a_1 = 7 )
- ( d = -3 ) (common difference)
- ( n = 20 )

[ a_n = a_1 + (n - 1)d ]

Substitute the given values:

[ a_n = 7 + (20 - 1)(-3) ]

[ a_n = 7 + 19(-3) ]

[ a_n = 7 - 57 ]

[ a_n = -50 ]

NowThe sum of an arithmetic sequence can be found using the formula:

[ S_n = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S_n ) is the sum of the first ( n ) terms,
- ( a_1 ) is the first term of the sequence,
- ( a_n ) is the ( n )-th term of the sequence,
- ( n ) is the number of terms in the sequence.

Given: ( a_1 = 7 ) (first term) ( d = -3 ) (common difference) ( n = 20 ) (number of terms)

[ a_n = a_1 + (n - 1)d ]

[ a_n = 7 + (20 - 1)(-3) ]

[ a_n = 7 + 19(-3) \The sum ( S ) of an arithmetic sequence can be found using the formula:

[ S = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S ) is the sum of the sequence
- ( n ) is the number of terms
- ( a_1 ) is the first term
- ( a_n ) is the ( n )th term

Given:

- ( a_1 = 7 )
- ( d = -3 ) (common difference)
- ( n = 20 )

[ a_n = a_1 + (n - 1)d ]

Substitute the given values:

[ a_n = 7 + (20 - 1)(-3) ]

[ a_n = 7 + 19(-3) ]

[ a_n = 7 - 57 ]

[ a_n = -50 ]

Now, substituteThe sum of an arithmetic sequence can be found using the formula:

[ S_n = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S_n ) is the sum of the first ( n ) terms,
- ( a_1 ) is the first term of the sequence,
- ( a_n ) is the ( n )-th term of the sequence,
- ( n ) is the number of terms in the sequence.

Given: ( a_1 = 7 ) (first term) ( d = -3 ) (common difference) ( n = 20 ) (number of terms)

[ a_n = a_1 + (n - 1)d ]

[ a_n = 7 + (20 - 1)(-3) ]

[ a_n = 7 + 19(-3) ]

[The sum ( S ) of an arithmetic sequence can be found using the formula:

[ S = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S ) is the sum of the sequence
- ( n ) is the number of terms
- ( a_1 ) is the first term
- ( a_n ) is the ( n )th term

Given:

- ( a_1 = 7 )
- ( d = -3 ) (common difference)
- ( n = 20 )

[ a_n = a_1 + (n - 1)d ]

Substitute the given values:

[ a_n = 7 + (20 - 1)(-3) ]

[ a_n = 7 + 19(-3) ]

[ a_n = 7 - 57 ]

[ a_n = -50 ]

Now, substitute ( a_The sum of an arithmetic sequence can be found using the formula:

[ S_n = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S_n ) is the sum of the first ( n ) terms,
- ( a_1 ) is the first term of the sequence,
- ( a_n ) is the ( n )-th term of the sequence,
- ( n ) is the number of terms in the sequence.

Given: ( a_1 = 7 ) (first term) ( d = -3 ) (common difference) ( n = 20 ) (number of terms)

[ a_n = a_1 + (n - 1)d ]

[ a_n = 7 + (20 - 1)(-3) ]

[ a_n = 7 + 19(-3) ]

[ a_n = 7 - 57 ]

[ a_n = -The sum ( S ) of an arithmetic sequence can be found using the formula:

[ S = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S ) is the sum of the sequence
- ( n ) is the number of terms
- ( a_1 ) is the first term
- ( a_n ) is the ( n )th term

Given:

- ( a_1 = 7 )
- ( d = -3 ) (common difference)
- ( n = 20 )

[ a_n = a_1 + (n - 1)d ]

Substitute the given values:

[ a_n = 7 + (20 - 1)(-3) ]

[ a_n = 7 + 19(-3) ]

[ a_n = 7 - 57 ]

[ a_n = -50 ]

Now, substitute ( a_1The sum of an arithmetic sequence can be found using the formula:

[ S_n = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S_n ) is the sum of the first ( n ) terms,
- ( a_1 ) is the first term of the sequence,
- ( a_n ) is the ( n )-th term of the sequence,
- ( n ) is the number of terms in the sequence.

Given: ( a_1 = 7 ) (first term) ( d = -3 ) (common difference) ( n = 20 ) (number of terms)

[ a_n = a_1 + (n - 1)d ]

[ a_n = 7 + (20 - 1)(-3) ]

[ a_n = 7 + 19(-3) ]

[ a_n = 7 - 57 ]

[ a_n = -50The sum ( S ) of an arithmetic sequence can be found using the formula:

[ S = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S ) is the sum of the sequence
- ( n ) is the number of terms
- ( a_1 ) is the first term
- ( a_n ) is the ( n )th term

Given:

- ( a_1 = 7 )
- ( d = -3 ) (common difference)
- ( n = 20 )

[ a_n = a_1 + (n - 1)d ]

Substitute the given values:

[ a_n = 7 + (20 - 1)(-3) ]

[ a_n = 7 + 19(-3) ]

[ a_n = 7 - 57 ]

[ a_n = -50 ]

Now, substitute ( a_1 =The sum of an arithmetic sequence can be found using the formula:

[ S_n = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S_n ) is the sum of the first ( n ) terms,
- ( a_1 ) is the first term of the sequence,
- ( a_n ) is the ( n )-th term of the sequence,
- ( n ) is the number of terms in the sequence.

Given: ( a_1 = 7 ) (first term) ( d = -3 ) (common difference) ( n = 20 ) (number of terms)

[ a_n = a_1 + (n - 1)d ]

[ a_n = 7 + (20 - 1)(-3) ]

[ a_n = 7 + 19(-3) ]

[ a_n = 7 - 57 ]

[ a_n = -50 ]

The sum ( S ) of an arithmetic sequence can be found using the formula:

[ S = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S ) is the sum of the sequence
- ( n ) is the number of terms
- ( a_1 ) is the first term
- ( a_n ) is the ( n )th term

Given:

- ( a_1 = 7 )
- ( d = -3 ) (common difference)
- ( n = 20 )

[ a_n = a_1 + (n - 1)d ]

Substitute the given values:

[ a_n = 7 + (20 - 1)(-3) ]

[ a_n = 7 + 19(-3) ]

[ a_n = 7 - 57 ]

[ a_n = -50 ]

Now, substitute ( a_1 = 7 \The sum of an arithmetic sequence can be found using the formula:

[ S_n = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S_n ) is the sum of the first ( n ) terms,
- ( a_1 ) is the first term of the sequence,
- ( a_n ) is the ( n )-th term of the sequence,
- ( n ) is the number of terms in the sequence.

Given: ( a_1 = 7 ) (first term) ( d = -3 ) (common difference) ( n = 20 ) (number of terms)

[ a_n = a_1 + (n - 1)d ]

[ a_n = 7 + (20 - 1)(-3) ]

[ a_n = 7 + 19(-3) ]

[ a_n = 7 - 57 ]

[ a_n = -50 ]

NowThe sum ( S ) of an arithmetic sequence can be found using the formula:

[ S = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S ) is the sum of the sequence
- ( n ) is the number of terms
- ( a_1 ) is the first term
- ( a_n ) is the ( n )th term

Given:

- ( a_1 = 7 )
- ( d = -3 ) (common difference)
- ( n = 20 )

[ a_n = a_1 + (n - 1)d ]

Substitute the given values:

[ a_n = 7 + (20 - 1)(-3) ]

[ a_n = 7 + 19(-3) ]

[ a_n = 7 - 57 ]

[ a_n = -50 ]

Now, substitute ( a_1 = 7 ),The sum of an arithmetic sequence can be found using the formula:

[ S_n = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S_n ) is the sum of the first ( n ) terms,
- ( a_1 ) is the first term of the sequence,
- ( a_n ) is the ( n )-th term of the sequence,
- ( n ) is the number of terms in the sequence.

Given: ( a_1 = 7 ) (first term) ( d = -3 ) (common difference) ( n = 20 ) (number of terms)

[ a_n = a_1 + (n - 1)d ]

[ a_n = 7 + (20 - 1)(-3) ]

[ a_n = 7 + 19(-3) ]

[ a_n = 7 - 57 ]

[ a_n = -50 ]

Now,The sum ( S ) of an arithmetic sequence can be found using the formula:

[ S = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S ) is the sum of the sequence
- ( n ) is the number of terms
- ( a_1 ) is the first term
- ( a_n ) is the ( n )th term

Given:

- ( a_1 = 7 )
- ( d = -3 ) (common difference)
- ( n = 20 )

[ a_n = a_1 + (n - 1)d ]

Substitute the given values:

[ a_n = 7 + (20 - 1)(-3) ]

[ a_n = 7 + 19(-3) ]

[ a_n = 7 - 57 ]

[ a_n = -50 ]

Now, substitute ( a_1 = 7 ), (The sum of an arithmetic sequence can be found using the formula:

[ S_n = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S_n ) is the sum of the first ( n ) terms,
- ( a_1 ) is the first term of the sequence,
- ( a_n ) is the ( n )-th term of the sequence,
- ( n ) is the number of terms in the sequence.

Given: ( a_1 = 7 ) (first term) ( d = -3 ) (common difference) ( n = 20 ) (number of terms)

[ a_n = a_1 + (n - 1)d ]

[ a_n = 7 + (20 - 1)(-3) ]

[ a_n = 7 + 19(-3) ]

[ a_n = 7 - 57 ]

[ a_n = -50 ]

Now, substituteThe sum ( S ) of an arithmetic sequence can be found using the formula:

[ S = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S ) is the sum of the sequence
- ( n ) is the number of terms
- ( a_1 ) is the first term
- ( a_n ) is the ( n )th term

Given:

- ( a_1 = 7 )
- ( d = -3 ) (common difference)
- ( n = 20 )

[ a_n = a_1 + (n - 1)d ]

Substitute the given values:

[ a_n = 7 + (20 - 1)(-3) ]

[ a_n = 7 + 19(-3) ]

[ a_n = 7 - 57 ]

[ a_n = -50 ]

Now, substitute ( a_1 = 7 ), ( a_nThe sum of an arithmetic sequence can be found using the formula:

[ S_n = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S_n ) is the sum of the first ( n ) terms,
- ( a_1 ) is the first term of the sequence,
- ( a_n ) is the ( n )-th term of the sequence,
- ( n ) is the number of terms in the sequence.

Given: ( a_1 = 7 ) (first term) ( d = -3 ) (common difference) ( n = 20 ) (number of terms)

[ a_n = a_1 + (n - 1)d ]

[ a_n = 7 + (20 - 1)(-3) ]

[ a_n = 7 + 19(-3) ]

[ a_n = 7 - 57 ]

[ a_n = -50 ]

Now, substitute theThe sum ( S ) of an arithmetic sequence can be found using the formula:

[ S = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S ) is the sum of the sequence
- ( n ) is the number of terms
- ( a_1 ) is the first term
- ( a_n ) is the ( n )th term

Given:

- ( a_1 = 7 )
- ( d = -3 ) (common difference)
- ( n = 20 )

[ a_n = a_1 + (n - 1)d ]

Substitute the given values:

[ a_n = 7 + (20 - 1)(-3) ]

[ a_n = 7 + 19(-3) ]

[ a_n = 7 - 57 ]

[ a_n = -50 ]

Now, substitute ( a_1 = 7 ), ( a_n = -The sum of an arithmetic sequence can be found using the formula:

[ S_n = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S_n ) is the sum of the first ( n ) terms,
- ( a_1 ) is the first term of the sequence,
- ( a_n ) is the ( n )-th term of the sequence,
- ( n ) is the number of terms in the sequence.

Given: ( a_1 = 7 ) (first term) ( d = -3 ) (common difference) ( n = 20 ) (number of terms)

[ a_n = a_1 + (n - 1)d ]

[ a_n = 7 + (20 - 1)(-3) ]

[ a_n = 7 + 19(-3) ]

[ a_n = 7 - 57 ]

[ a_n = -50 ]

Now, substitute the valuesThe sum ( S ) of an arithmetic sequence can be found using the formula:

[ S = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S ) is the sum of the sequence
- ( n ) is the number of terms
- ( a_1 ) is the first term
- ( a_n ) is the ( n )th term

Given:

- ( a_1 = 7 )
- ( d = -3 ) (common difference)
- ( n = 20 )

[ a_n = a_1 + (n - 1)d ]

Substitute the given values:

[ a_n = 7 + (20 - 1)(-3) ]

[ a_n = 7 + 19(-3) ]

[ a_n = 7 - 57 ]

[ a_n = -50 ]

Now, substitute ( a_1 = 7 ), ( a_n = -50The sum of an arithmetic sequence can be found using the formula:

[ S_n = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S_n ) is the sum of the first ( n ) terms,
- ( a_1 ) is the first term of the sequence,
- ( a_n ) is the ( n )-th term of the sequence,
- ( n ) is the number of terms in the sequence.

Given: ( a_1 = 7 ) (first term) ( d = -3 ) (common difference) ( n = 20 ) (number of terms)

[ a_n = a_1 + (n - 1)d ]

[ a_n = 7 + (20 - 1)(-3) ]

[ a_n = 7 + 19(-3) ]

[ a_n = 7 - 57 ]

[ a_n = -50 ]

Now, substitute the values ofThe sum ( S ) of an arithmetic sequence can be found using the formula:

[ S = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S ) is the sum of the sequence
- ( n ) is the number of terms
- ( a_1 ) is the first term
- ( a_n ) is the ( n )th term

Given:

- ( a_1 = 7 )
- ( d = -3 ) (common difference)
- ( n = 20 )

[ a_n = a_1 + (n - 1)d ]

Substitute the given values:

[ a_n = 7 + (20 - 1)(-3) ]

[ a_n = 7 + 19(-3) ]

[ a_n = 7 - 57 ]

[ a_n = -50 ]

Now, substitute ( a_1 = 7 ), ( a_n = -50 \The sum of an arithmetic sequence can be found using the formula:

[ S_n = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S_n ) is the sum of the first ( n ) terms,
- ( a_1 ) is the first term of the sequence,
- ( a_n ) is the ( n )-th term of the sequence,
- ( n ) is the number of terms in the sequence.

Given: ( a_1 = 7 ) (first term) ( d = -3 ) (common difference) ( n = 20 ) (number of terms)

[ a_n = a_1 + (n - 1)d ]

[ a_n = 7 + (20 - 1)(-3) ]

[ a_n = 7 + 19(-3) ]

[ a_n = 7 - 57 ]

[ a_n = -50 ]

Now, substitute the values of (The sum ( S ) of an arithmetic sequence can be found using the formula:

[ S = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S ) is the sum of the sequence
- ( n ) is the number of terms
- ( a_1 ) is the first term
- ( a_n ) is the ( n )th term

Given:

- ( a_1 = 7 )
- ( d = -3 ) (common difference)
- ( n = 20 )

[ a_n = a_1 + (n - 1)d ]

Substitute the given values:

[ a_n = 7 + (20 - 1)(-3) ]

[ a_n = 7 + 19(-3) ]

[ a_n = 7 - 57 ]

[ a_n = -50 ]

Now, substitute ( a_1 = 7 ), ( a_n = -50 ),The sum of an arithmetic sequence can be found using the formula:

[ S_n = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S_n ) is the sum of the first ( n ) terms,
- ( a_1 ) is the first term of the sequence,
- ( a_n ) is the ( n )-th term of the sequence,
- ( n ) is the number of terms in the sequence.

Given: ( a_1 = 7 ) (first term) ( d = -3 ) (common difference) ( n = 20 ) (number of terms)

[ a_n = a_1 + (n - 1)d ]

[ a_n = 7 + (20 - 1)(-3) ]

[ a_n = 7 + 19(-3) ]

[ a_n = 7 - 57 ]

[ a_n = -50 ]

Now, substitute the values of ( aThe sum ( S ) of an arithmetic sequence can be found using the formula:

[ S = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S ) is the sum of the sequence
- ( n ) is the number of terms
- ( a_1 ) is the first term
- ( a_n ) is the ( n )th term

Given:

- ( a_1 = 7 )
- ( d = -3 ) (common difference)
- ( n = 20 )

[ a_n = a_1 + (n - 1)d ]

Substitute the given values:

[ a_n = 7 + (20 - 1)(-3) ]

[ a_n = 7 + 19(-3) ]

[ a_n = 7 - 57 ]

[ a_n = -50 ]

Now, substitute ( a_1 = 7 ), ( a_n = -50 ), andThe sum of an arithmetic sequence can be found using the formula:

[ S_n = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S_n ) is the sum of the first ( n ) terms,
- ( a_1 ) is the first term of the sequence,
- ( a_n ) is the ( n )-th term of the sequence,
- ( n ) is the number of terms in the sequence.

Given: ( a_1 = 7 ) (first term) ( d = -3 ) (common difference) ( n = 20 ) (number of terms)

[ a_n = a_1 + (n - 1)d ]

[ a_n = 7 + (20 - 1)(-3) ]

[ a_n = 7 + 19(-3) ]

[ a_n = 7 - 57 ]

[ a_n = -50 ]

Now, substitute the values of ( a_The sum ( S ) of an arithmetic sequence can be found using the formula:

[ S = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S ) is the sum of the sequence
- ( n ) is the number of terms
- ( a_1 ) is the first term
- ( a_n ) is the ( n )th term

Given:

- ( a_1 = 7 )
- ( d = -3 ) (common difference)
- ( n = 20 )

[ a_n = a_1 + (n - 1)d ]

Substitute the given values:

[ a_n = 7 + (20 - 1)(-3) ]

[ a_n = 7 + 19(-3) ]

[ a_n = 7 - 57 ]

[ a_n = -50 ]

Now, substitute ( a_1 = 7 ), ( a_n = -50 ), and ( n =The sum of an arithmetic sequence can be found using the formula:

[ S_n = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S_n ) is the sum of the first ( n ) terms,
- ( a_1 ) is the first term of the sequence,
- ( a_n ) is the ( n )-th term of the sequence,
- ( n ) is the number of terms in the sequence.

Given: ( a_1 = 7 ) (first term) ( d = -3 ) (common difference) ( n = 20 ) (number of terms)

[ a_n = a_1 + (n - 1)d ]

[ a_n = 7 + (20 - 1)(-3) ]

[ a_n = 7 + 19(-3) ]

[ a_n = 7 - 57 ]

[ a_n = -50 ]

Now, substitute the values of ( a_1The sum ( S ) of an arithmetic sequence can be found using the formula:

[ S = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S ) is the sum of the sequence
- ( n ) is the number of terms
- ( a_1 ) is the first term
- ( a_n ) is the ( n )th term

Given:

- ( a_1 = 7 )
- ( d = -3 ) (common difference)
- ( n = 20 )

[ a_n = a_1 + (n - 1)d ]

Substitute the given values:

[ a_n = 7 + (20 - 1)(-3) ]

[ a_n = 7 + 19(-3) ]

[ a_n = 7 - 57 ]

[ a_n = -50 ]

Now, substitute ( a_1 = 7 ), ( a_n = -50 ), and ( n = 20The sum of an arithmetic sequence can be found using the formula:

[ S_n = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S_n ) is the sum of the first ( n ) terms,
- ( a_1 ) is the first term of the sequence,
- ( a_n ) is the ( n )-th term of the sequence,
- ( n ) is the number of terms in the sequence.

Given: ( a_1 = 7 ) (first term) ( d = -3 ) (common difference) ( n = 20 ) (number of terms)

[ a_n = a_1 + (n - 1)d ]

[ a_n = 7 + (20 - 1)(-3) ]

[ a_n = 7 + 19(-3) ]

[ a_n = 7 - 57 ]

[ a_n = -50 ]

Now, substitute the values of ( a_1 \The sum ( S ) of an arithmetic sequence can be found using the formula:

[ S = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S ) is the sum of the sequence
- ( n ) is the number of terms
- ( a_1 ) is the first term
- ( a_n ) is the ( n )th term

Given:

- ( a_1 = 7 )
- ( d = -3 ) (common difference)
- ( n = 20 )

[ a_n = a_1 + (n - 1)d ]

Substitute the given values:

[ a_n = 7 + (20 - 1)(-3) ]

[ a_n = 7 + 19(-3) ]

[ a_n = 7 - 57 ]

[ a_n = -50 ]

Now, substitute ( a_1 = 7 ), ( a_n = -50 ), and ( n = 20 \The sum of an arithmetic sequence can be found using the formula:

[ S_n = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S_n ) is the sum of the first ( n ) terms,
- ( a_1 ) is the first term of the sequence,
- ( a_n ) is the ( n )-th term of the sequence,
- ( n ) is the number of terms in the sequence.

Given: ( a_1 = 7 ) (first term) ( d = -3 ) (common difference) ( n = 20 ) (number of terms)

[ a_n = a_1 + (n - 1)d ]

[ a_n = 7 + (20 - 1)(-3) ]

[ a_n = 7 + 19(-3) ]

[ a_n = 7 - 57 ]

[ a_n = -50 ]

Now, substitute the values of ( a_1 ) andThe sum ( S ) of an arithmetic sequence can be found using the formula:

[ S = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S ) is the sum of the sequence
- ( n ) is the number of terms
- ( a_1 ) is the first term
- ( a_n ) is the ( n )th term

Given:

- ( a_1 = 7 )
- ( d = -3 ) (common difference)
- ( n = 20 )

[ a_n = a_1 + (n - 1)d ]

Substitute the given values:

[ a_n = 7 + (20 - 1)(-3) ]

[ a_n = 7 + 19(-3) ]

[ a_n = 7 - 57 ]

[ a_n = -50 ]

Now, substitute ( a_1 = 7 ), ( a_n = -50 ), and ( n = 20 ) intoThe sum of an arithmetic sequence can be found using the formula:

[ S_n = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S_n ) is the sum of the first ( n ) terms,
- ( a_1 ) is the first term of the sequence,
- ( a_n ) is the ( n )-th term of the sequence,
- ( n ) is the number of terms in the sequence.

Given: ( a_1 = 7 ) (first term) ( d = -3 ) (common difference) ( n = 20 ) (number of terms)

[ a_n = a_1 + (n - 1)d ]

[ a_n = 7 + (20 - 1)(-3) ]

[ a_n = 7 + 19(-3) ]

[ a_n = 7 - 57 ]

[ a_n = -50 ]

Now, substitute the values of ( a_1 ) and ( a_nThe sum ( S ) of an arithmetic sequence can be found using the formula:

[ S = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S ) is the sum of the sequence
- ( n ) is the number of terms
- ( a_1 ) is the first term
- ( a_n ) is the ( n )th term

Given:

- ( a_1 = 7 )
- ( d = -3 ) (common difference)
- ( n = 20 )

[ a_n = a_1 + (n - 1)d ]

Substitute the given values:

[ a_n = 7 + (20 - 1)(-3) ]

[ a_n = 7 + 19(-3) ]

[ a_n = 7 - 57 ]

[ a_n = -50 ]

Now, substitute ( a_1 = 7 ), ( a_n = -50 ), and ( n = 20 ) into theThe sum of an arithmetic sequence can be found using the formula:

[ S_n = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S_n ) is the sum of the first ( n ) terms,
- ( a_1 ) is the first term of the sequence,
- ( a_n ) is the ( n )-th term of the sequence,
- ( n ) is the number of terms in the sequence.

Given: ( a_1 = 7 ) (first term) ( d = -3 ) (common difference) ( n = 20 ) (number of terms)

[ a_n = a_1 + (n - 1)d ]

[ a_n = 7 + (20 - 1)(-3) ]

[ a_n = 7 + 19(-3) ]

[ a_n = 7 - 57 ]

[ a_n = -50 ]

Now, substitute the values of ( a_1 ) and ( a_n )The sum ( S ) of an arithmetic sequence can be found using the formula:

[ S = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S ) is the sum of the sequence
- ( n ) is the number of terms
- ( a_1 ) is the first term
- ( a_n ) is the ( n )th term

Given:

- ( a_1 = 7 )
- ( d = -3 ) (common difference)
- ( n = 20 )

[ a_n = a_1 + (n - 1)d ]

Substitute the given values:

[ a_n = 7 + (20 - 1)(-3) ]

[ a_n = 7 + 19(-3) ]

[ a_n = 7 - 57 ]

[ a_n = -50 ]

Now, substitute ( a_1 = 7 ), ( a_n = -50 ), and ( n = 20 ) into the sumThe sum of an arithmetic sequence can be found using the formula:

[ S_n = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S_n ) is the sum of the first ( n ) terms,
- ( a_1 ) is the first term of the sequence,
- ( a_n ) is the ( n )-th term of the sequence,
- ( n ) is the number of terms in the sequence.

Given: ( a_1 = 7 ) (first term) ( d = -3 ) (common difference) ( n = 20 ) (number of terms)

[ a_n = a_1 + (n - 1)d ]

[ a_n = 7 + (20 - 1)(-3) ]

[ a_n = 7 + 19(-3) ]

[ a_n = 7 - 57 ]

[ a_n = -50 ]

Now, substitute the values of ( a_1 ) and ( a_n ) into theThe sum ( S ) of an arithmetic sequence can be found using the formula:

[ S = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S ) is the sum of the sequence
- ( n ) is the number of terms
- ( a_1 ) is the first term
- ( a_n ) is the ( n )th term

Given:

- ( a_1 = 7 )
- ( d = -3 ) (common difference)
- ( n = 20 )

[ a_n = a_1 + (n - 1)d ]

Substitute the given values:

[ a_n = 7 + (20 - 1)(-3) ]

[ a_n = 7 + 19(-3) ]

[ a_n = 7 - 57 ]

[ a_n = -50 ]

Now, substitute ( a_1 = 7 ), ( a_n = -50 ), and ( n = 20 ) into the sum formulaThe sum of an arithmetic sequence can be found using the formula:

[ S_n = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S_n ) is the sum of the first ( n ) terms,
- ( a_1 ) is the first term of the sequence,
- ( a_n ) is the ( n )-th term of the sequence,
- ( n ) is the number of terms in the sequence.

Given: ( a_1 = 7 ) (first term) ( d = -3 ) (common difference) ( n = 20 ) (number of terms)

[ a_n = a_1 + (n - 1)d ]

[ a_n = 7 + (20 - 1)(-3) ]

[ a_n = 7 + 19(-3) ]

[ a_n = 7 - 57 ]

[ a_n = -50 ]

Now, substitute the values of ( a_1 ) and ( a_n ) into the sum formula:

The sum ( S ) of an arithmetic sequence can be found using the formula:

[ S = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S ) is the sum of the sequence
- ( n ) is the number of terms
- ( a_1 ) is the first term
- ( a_n ) is the ( n )th term

Given:

- ( a_1 = 7 )
- ( d = -3 ) (common difference)
- ( n = 20 )

[ a_n = a_1 + (n - 1)d ]

Substitute the given values:

[ a_n = 7 + (20 - 1)(-3) ]

[ a_n = 7 + 19(-3) ]

[ a_n = 7 - 57 ]

[ a_n = -50 ]

Now, substitute ( a_1 = 7 ), ( a_n = -50 ), and ( n = 20 ) into the sum formula:

[The sum of an arithmetic sequence can be found using the formula:

[ S_n = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S_n ) is the sum of the first ( n ) terms,
- ( a_1 ) is the first term of the sequence,
- ( a_n ) is the ( n )-th term of the sequence,
- ( n ) is the number of terms in the sequence.

Given: ( a_1 = 7 ) (first term) ( d = -3 ) (common difference) ( n = 20 ) (number of terms)

[ a_n = a_1 + (n - 1)d ]

[ a_n = 7 + (20 - 1)(-3) ]

[ a_n = 7 + 19(-3) ]

[ a_n = 7 - 57 ]

[ a_n = -50 ]

Now, substitute the values of ( a_1 ) and ( a_n ) into the sum formula:

[The sum ( S ) of an arithmetic sequence can be found using the formula:

[ S = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S ) is the sum of the sequence
- ( n ) is the number of terms
- ( a_1 ) is the first term
- ( a_n ) is the ( n )th term

Given:

- ( a_1 = 7 )
- ( d = -3 ) (common difference)
- ( n = 20 )

[ a_n = a_1 + (n - 1)d ]

Substitute the given values:

[ a_n = 7 + (20 - 1)(-3) ]

[ a_n = 7 + 19(-3) ]

[ a_n = 7 - 57 ]

[ a_n = -50 ]

Now, substitute ( a_1 = 7 ), ( a_n = -50 ), and ( n = 20 ) into the sum formula:

[ SThe sum of an arithmetic sequence can be found using the formula:

[ S_n = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S_n ) is the sum of the first ( n ) terms,
- ( a_1 ) is the first term of the sequence,
- ( a_n ) is the ( n )-th term of the sequence,
- ( n ) is the number of terms in the sequence.

Given: ( a_1 = 7 ) (first term) ( d = -3 ) (common difference) ( n = 20 ) (number of terms)

[ a_n = a_1 + (n - 1)d ]

[ a_n = 7 + (20 - 1)(-3) ]

[ a_n = 7 + 19(-3) ]

[ a_n = 7 - 57 ]

[ a_n = -50 ]

Now, substitute the values of ( a_1 ) and ( a_n ) into the sum formula:

[ SThe sum ( S ) of an arithmetic sequence can be found using the formula:

[ S = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S ) is the sum of the sequence
- ( n ) is the number of terms
- ( a_1 ) is the first term
- ( a_n ) is the ( n )th term

Given:

- ( a_1 = 7 )
- ( d = -3 ) (common difference)
- ( n = 20 )

[ a_n = a_1 + (n - 1)d ]

Substitute the given values:

[ a_n = 7 + (20 - 1)(-3) ]

[ a_n = 7 + 19(-3) ]

[ a_n = 7 - 57 ]

[ a_n = -50 ]

Now, substitute ( a_1 = 7 ), ( a_n = -50 ), and ( n = 20 ) into the sum formula:

[ S = \The sum of an arithmetic sequence can be found using the formula:

[ S_n = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S_n ) is the sum of the first ( n ) terms,
- ( a_1 ) is the first term of the sequence,
- ( a_n ) is the ( n )-th term of the sequence,
- ( n ) is the number of terms in the sequence.

Given: ( a_1 = 7 ) (first term) ( d = -3 ) (common difference) ( n = 20 ) (number of terms)

[ a_n = a_1 + (n - 1)d ]

[ a_n = 7 + (20 - 1)(-3) ]

[ a_n = 7 + 19(-3) ]

[ a_n = 7 - 57 ]

[ a_n = -50 ]

Now, substitute the values of ( a_1 ) and ( a_n ) into the sum formula:

[ S_{20The sum ( S ) of an arithmetic sequence can be found using the formula:

[ S = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S ) is the sum of the sequence
- ( n ) is the number of terms
- ( a_1 ) is the first term
- ( a_n ) is the ( n )th term

Given:

- ( a_1 = 7 )
- ( d = -3 ) (common difference)
- ( n = 20 )

[ a_n = a_1 + (n - 1)d ]

Substitute the given values:

[ a_n = 7 + (20 - 1)(-3) ]

[ a_n = 7 + 19(-3) ]

[ a_n = 7 - 57 ]

[ a_n = -50 ]

Now, substitute ( a_1 = 7 ), ( a_n = -50 ), and ( n = 20 ) into the sum formula:

[ S = \fracThe sum of an arithmetic sequence can be found using the formula:

[ S_n = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S_n ) is the sum of the first ( n ) terms,
- ( a_1 ) is the first term of the sequence,
- ( a_n ) is the ( n )-th term of the sequence,
- ( n ) is the number of terms in the sequence.

Given: ( a_1 = 7 ) (first term) ( d = -3 ) (common difference) ( n = 20 ) (number of terms)

[ a_n = a_1 + (n - 1)d ]

[ a_n = 7 + (20 - 1)(-3) ]

[ a_n = 7 + 19(-3) ]

[ a_n = 7 - 57 ]

[ a_n = -50 ]

Now, substitute the values of ( a_1 ) and ( a_n ) into the sum formula:

[ S_{20}The sum ( S ) of an arithmetic sequence can be found using the formula:

[ S = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S ) is the sum of the sequence
- ( n ) is the number of terms
- ( a_1 ) is the first term
- ( a_n ) is the ( n )th term

Given:

- ( a_1 = 7 )
- ( d = -3 ) (common difference)
- ( n = 20 )

[ a_n = a_1 + (n - 1)d ]

Substitute the given values:

[ a_n = 7 + (20 - 1)(-3) ]

[ a_n = 7 + 19(-3) ]

[ a_n = 7 - 57 ]

[ a_n = -50 ]

Now, substitute ( a_1 = 7 ), ( a_n = -50 ), and ( n = 20 ) into the sum formula:

[ S = \frac{The sum of an arithmetic sequence can be found using the formula:

[ S_n = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S_n ) is the sum of the first ( n ) terms,
- ( a_1 ) is the first term of the sequence,
- ( a_n ) is the ( n )-th term of the sequence,
- ( n ) is the number of terms in the sequence.

Given: ( a_1 = 7 ) (first term) ( d = -3 ) (common difference) ( n = 20 ) (number of terms)

[ a_n = a_1 + (n - 1)d ]

[ a_n = 7 + (20 - 1)(-3) ]

[ a_n = 7 + 19(-3) ]

[ a_n = 7 - 57 ]

[ a_n = -50 ]

Now, substitute the values of ( a_1 ) and ( a_n ) into the sum formula:

[ S_{20} =The sum ( S ) of an arithmetic sequence can be found using the formula:

[ S = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S ) is the sum of the sequence
- ( n ) is the number of terms
- ( a_1 ) is the first term
- ( a_n ) is the ( n )th term

Given:

- ( a_1 = 7 )
- ( d = -3 ) (common difference)
- ( n = 20 )

[ a_n = a_1 + (n - 1)d ]

Substitute the given values:

[ a_n = 7 + (20 - 1)(-3) ]

[ a_n = 7 + 19(-3) ]

[ a_n = 7 - 57 ]

[ a_n = -50 ]

Now, substitute ( a_1 = 7 ), ( a_n = -50 ), and ( n = 20 ) into the sum formula:

[ S = \frac{20The sum of an arithmetic sequence can be found using the formula:

[ S_n = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S_n ) is the sum of the first ( n ) terms,
- ( a_1 ) is the first term of the sequence,
- ( a_n ) is the ( n )-th term of the sequence,
- ( n ) is the number of terms in the sequence.

Given: ( a_1 = 7 ) (first term) ( d = -3 ) (common difference) ( n = 20 ) (number of terms)

[ a_n = a_1 + (n - 1)d ]

[ a_n = 7 + (20 - 1)(-3) ]

[ a_n = 7 + 19(-3) ]

[ a_n = 7 - 57 ]

[ a_n = -50 ]

Now, substitute the values of ( a_1 ) and ( a_n ) into the sum formula:

[ S_{20} = \The sum ( S ) of an arithmetic sequence can be found using the formula:

[ S = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S ) is the sum of the sequence
- ( n ) is the number of terms
- ( a_1 ) is the first term
- ( a_n ) is the ( n )th term

Given:

- ( a_1 = 7 )
- ( d = -3 ) (common difference)
- ( n = 20 )

[ a_n = a_1 + (n - 1)d ]

Substitute the given values:

[ a_n = 7 + (20 - 1)(-3) ]

[ a_n = 7 + 19(-3) ]

[ a_n = 7 - 57 ]

[ a_n = -50 ]

Now, substitute ( a_1 = 7 ), ( a_n = -50 ), and ( n = 20 ) into the sum formula:

[ S = \frac{20}{2The sum of an arithmetic sequence can be found using the formula:

[ S_n = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S_n ) is the sum of the first ( n ) terms,
- ( a_1 ) is the first term of the sequence,
- ( a_n ) is the ( n )-th term of the sequence,
- ( n ) is the number of terms in the sequence.

Given: ( a_1 = 7 ) (first term) ( d = -3 ) (common difference) ( n = 20 ) (number of terms)

[ a_n = a_1 + (n - 1)d ]

[ a_n = 7 + (20 - 1)(-3) ]

[ a_n = 7 + 19(-3) ]

[ a_n = 7 - 57 ]

[ a_n = -50 ]

Now, substitute the values of ( a_1 ) and ( a_n ) into the sum formula:

[ S_{20} = \fracThe sum ( S ) of an arithmetic sequence can be found using the formula:

[ S = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S ) is the sum of the sequence
- ( n ) is the number of terms
- ( a_1 ) is the first term
- ( a_n ) is the ( n )th term

Given:

- ( a_1 = 7 )
- ( d = -3 ) (common difference)
- ( n = 20 )

[ a_n = a_1 + (n - 1)d ]

Substitute the given values:

[ a_n = 7 + (20 - 1)(-3) ]

[ a_n = 7 + 19(-3) ]

[ a_n = 7 - 57 ]

[ a_n = -50 ]

Now, substitute ( a_1 = 7 ), ( a_n = -50 ), and ( n = 20 ) into the sum formula:

[ S = \frac{20}{2}(The sum of an arithmetic sequence can be found using the formula:

[ S_n = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S_n ) is the sum of the first ( n ) terms,
- ( a_1 ) is the first term of the sequence,
- ( a_n ) is the ( n )-th term of the sequence,
- ( n ) is the number of terms in the sequence.

Given: ( a_1 = 7 ) (first term) ( d = -3 ) (common difference) ( n = 20 ) (number of terms)

[ a_n = a_1 + (n - 1)d ]

[ a_n = 7 + (20 - 1)(-3) ]

[ a_n = 7 + 19(-3) ]

[ a_n = 7 - 57 ]

[ a_n = -50 ]

Now, substitute the values of ( a_1 ) and ( a_n ) into the sum formula:

[ S_{20} = \frac{The sum ( S ) of an arithmetic sequence can be found using the formula:

[ S = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S ) is the sum of the sequence
- ( n ) is the number of terms
- ( a_1 ) is the first term
- ( a_n ) is the ( n )th term

Given:

- ( a_1 = 7 )
- ( d = -3 ) (common difference)
- ( n = 20 )

[ a_n = a_1 + (n - 1)d ]

Substitute the given values:

[ a_n = 7 + (20 - 1)(-3) ]

[ a_n = 7 + 19(-3) ]

[ a_n = 7 - 57 ]

[ a_n = -50 ]

Now, substitute ( a_1 = 7 ), ( a_n = -50 ), and ( n = 20 ) into the sum formula:

[ S = \frac{20}{2}(7The sum of an arithmetic sequence can be found using the formula:

[ S_n = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S_n ) is the sum of the first ( n ) terms,
- ( a_1 ) is the first term of the sequence,
- ( a_n ) is the ( n )-th term of the sequence,
- ( n ) is the number of terms in the sequence.

Given: ( a_1 = 7 ) (first term) ( d = -3 ) (common difference) ( n = 20 ) (number of terms)

[ a_n = a_1 + (n - 1)d ]

[ a_n = 7 + (20 - 1)(-3) ]

[ a_n = 7 + 19(-3) ]

[ a_n = 7 - 57 ]

[ a_n = -50 ]

Now, substitute the values of ( a_1 ) and ( a_n ) into the sum formula:

[ S_{20} = \frac{20The sum ( S ) of an arithmetic sequence can be found using the formula:

[ S = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S ) is the sum of the sequence
- ( n ) is the number of terms
- ( a_1 ) is the first term
- ( a_n ) is the ( n )th term

Given:

- ( a_1 = 7 )
- ( d = -3 ) (common difference)
- ( n = 20 )

[ a_n = a_1 + (n - 1)d ]

Substitute the given values:

[ a_n = 7 + (20 - 1)(-3) ]

[ a_n = 7 + 19(-3) ]

[ a_n = 7 - 57 ]

[ a_n = -50 ]

Now, substitute ( a_1 = 7 ), ( a_n = -50 ), and ( n = 20 ) into the sum formula:

[ S = \frac{20}{2}(7 -The sum of an arithmetic sequence can be found using the formula:

[ S_n = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S_n ) is the sum of the first ( n ) terms,
- ( a_1 ) is the first term of the sequence,
- ( a_n ) is the ( n )-th term of the sequence,
- ( n ) is the number of terms in the sequence.

Given: ( a_1 = 7 ) (first term) ( d = -3 ) (common difference) ( n = 20 ) (number of terms)

[ a_n = a_1 + (n - 1)d ]

[ a_n = 7 + (20 - 1)(-3) ]

[ a_n = 7 + 19(-3) ]

[ a_n = 7 - 57 ]

[ a_n = -50 ]

Now, substitute the values of ( a_1 ) and ( a_n ) into the sum formula:

[ S_{20} = \frac{20}{The sum ( S ) of an arithmetic sequence can be found using the formula:

[ S = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S ) is the sum of the sequence
- ( n ) is the number of terms
- ( a_1 ) is the first term
- ( a_n ) is the ( n )th term

Given:

- ( a_1 = 7 )
- ( d = -3 ) (common difference)
- ( n = 20 )

[ a_n = a_1 + (n - 1)d ]

Substitute the given values:

[ a_n = 7 + (20 - 1)(-3) ]

[ a_n = 7 + 19(-3) ]

[ a_n = 7 - 57 ]

[ a_n = -50 ]

Now, substitute ( a_1 = 7 ), ( a_n = -50 ), and ( n = 20 ) into the sum formula:

[ S = \frac{20}{2}(7 - The sum of an arithmetic sequence can be found using the formula:

[ S_n = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S_n ) is the sum of the first ( n ) terms,
- ( a_1 ) is the first term of the sequence,
- ( a_n ) is the ( n )-th term of the sequence,
- ( n ) is the number of terms in the sequence.

Given: ( a_1 = 7 ) (first term) ( d = -3 ) (common difference) ( n = 20 ) (number of terms)

[ a_n = a_1 + (n - 1)d ]

[ a_n = 7 + (20 - 1)(-3) ]

[ a_n = 7 + 19(-3) ]

[ a_n = 7 - 57 ]

[ a_n = -50 ]

Now, substitute the values of ( a_1 ) and ( a_n ) into the sum formula:

[ S_{20} = \frac{20}{2The sum ( S ) of an arithmetic sequence can be found using the formula:

[ S = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S ) is the sum of the sequence
- ( n ) is the number of terms
- ( a_1 ) is the first term
- ( a_n ) is the ( n )th term

Given:

- ( a_1 = 7 )
- ( d = -3 ) (common difference)
- ( n = 20 )

[ a_n = a_1 + (n - 1)d ]

Substitute the given values:

[ a_n = 7 + (20 - 1)(-3) ]

[ a_n = 7 + 19(-3) ]

[ a_n = 7 - 57 ]

[ a_n = -50 ]

Now, substitute ( a_1 = 7 ), ( a_n = -50 ), and ( n = 20 ) into the sum formula:

[ S = \frac{20}{2}(7 - 50)The sum of an arithmetic sequence can be found using the formula:

[ S_n = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S_n ) is the sum of the first ( n ) terms,
- ( a_1 ) is the first term of the sequence,
- ( a_n ) is the ( n )-th term of the sequence,
- ( n ) is the number of terms in the sequence.

Given: ( a_1 = 7 ) (first term) ( d = -3 ) (common difference) ( n = 20 ) (number of terms)

[ a_n = a_1 + (n - 1)d ]

[ a_n = 7 + (20 - 1)(-3) ]

[ a_n = 7 + 19(-3) ]

[ a_n = 7 - 57 ]

[ a_n = -50 ]

Now, substitute the values of ( a_1 ) and ( a_n ) into the sum formula:

[ S_{20} = \frac{20}{2}(The sum ( S ) of an arithmetic sequence can be found using the formula:

[ S = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S ) is the sum of the sequence
- ( n ) is the number of terms
- ( a_1 ) is the first term
- ( a_n ) is the ( n )th term

Given:

- ( a_1 = 7 )
- ( d = -3 ) (common difference)
- ( n = 20 )

[ a_n = a_1 + (n - 1)d ]

Substitute the given values:

[ a_n = 7 + (20 - 1)(-3) ]

[ a_n = 7 + 19(-3) ]

[ a_n = 7 - 57 ]

[ a_n = -50 ]

Now, substitute ( a_1 = 7 ), ( a_n = -50 ), and ( n = 20 ) into the sum formula:

[ S = \frac{20}{2}(7 - 50) \The sum of an arithmetic sequence can be found using the formula:

[ S_n = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S_n ) is the sum of the first ( n ) terms,
- ( a_1 ) is the first term of the sequence,
- ( a_n ) is the ( n )-th term of the sequence,
- ( n ) is the number of terms in the sequence.

Given: ( a_1 = 7 ) (first term) ( d = -3 ) (common difference) ( n = 20 ) (number of terms)

[ a_n = a_1 + (n - 1)d ]

[ a_n = 7 + (20 - 1)(-3) ]

[ a_n = 7 + 19(-3) ]

[ a_n = 7 - 57 ]

[ a_n = -50 ]

Now, substitute the values of ( a_1 ) and ( a_n ) into the sum formula:

[ S_{20} = \frac{20}{2}(7The sum ( S ) of an arithmetic sequence can be found using the formula:

[ S = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S ) is the sum of the sequence
- ( n ) is the number of terms
- ( a_1 ) is the first term
- ( a_n ) is the ( n )th term

Given:

- ( a_1 = 7 )
- ( d = -3 ) (common difference)
- ( n = 20 )

[ a_n = a_1 + (n - 1)d ]

Substitute the given values:

[ a_n = 7 + (20 - 1)(-3) ]

[ a_n = 7 + 19(-3) ]

[ a_n = 7 - 57 ]

[ a_n = -50 ]

Now, substitute ( a_1 = 7 ), ( a_n = -50 ), and ( n = 20 ) into the sum formula:

[ S = \frac{20}{2}(7 - 50) ]

The sum of an arithmetic sequence can be found using the formula:

[ S_n = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S_n ) is the sum of the first ( n ) terms,
- ( a_1 ) is the first term of the sequence,
- ( a_n ) is the ( n )-th term of the sequence,
- ( n ) is the number of terms in the sequence.

Given: ( a_1 = 7 ) (first term) ( d = -3 ) (common difference) ( n = 20 ) (number of terms)

[ a_n = a_1 + (n - 1)d ]

[ a_n = 7 + (20 - 1)(-3) ]

[ a_n = 7 + 19(-3) ]

[ a_n = 7 - 57 ]

[ a_n = -50 ]

Now, substitute the values of ( a_1 ) and ( a_n ) into the sum formula:

[ S_{20} = \frac{20}{2}(7 + (-The sum ( S ) of an arithmetic sequence can be found using the formula:

[ S = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S ) is the sum of the sequence
- ( n ) is the number of terms
- ( a_1 ) is the first term
- ( a_n ) is the ( n )th term

Given:

- ( a_1 = 7 )
- ( d = -3 ) (common difference)
- ( n = 20 )

[ a_n = a_1 + (n - 1)d ]

Substitute the given values:

[ a_n = 7 + (20 - 1)(-3) ]

[ a_n = 7 + 19(-3) ]

[ a_n = 7 - 57 ]

[ a_n = -50 ]

Now, substitute ( a_1 = 7 ), ( a_n = -50 ), and ( n = 20 ) into the sum formula:

[ S = \frac{20}{2}(7 - 50) ]

[ SThe sum of an arithmetic sequence can be found using the formula:

[ S_n = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S_n ) is the sum of the first ( n ) terms,
- ( a_1 ) is the first term of the sequence,
- ( a_n ) is the ( n )-th term of the sequence,
- ( n ) is the number of terms in the sequence.

Given: ( a_1 = 7 ) (first term) ( d = -3 ) (common difference) ( n = 20 ) (number of terms)

[ a_n = a_1 + (n - 1)d ]

[ a_n = 7 + (20 - 1)(-3) ]

[ a_n = 7 + 19(-3) ]

[ a_n = 7 - 57 ]

[ a_n = -50 ]

Now, substitute the values of ( a_1 ) and ( a_n ) into the sum formula:

[ S_{20} = \frac{20}{2}(7 + (-50The sum ( S ) of an arithmetic sequence can be found using the formula:

[ S = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S ) is the sum of the sequence
- ( n ) is the number of terms
- ( a_1 ) is the first term
- ( a_n ) is the ( n )th term

Given:

- ( a_1 = 7 )
- ( d = -3 ) (common difference)
- ( n = 20 )

[ a_n = a_1 + (n - 1)d ]

Substitute the given values:

[ a_n = 7 + (20 - 1)(-3) ]

[ a_n = 7 + 19(-3) ]

[ a_n = 7 - 57 ]

[ a_n = -50 ]

Now, substitute ( a_1 = 7 ), ( a_n = -50 ), and ( n = 20 ) into the sum formula:

[ S = \frac{20}{2}(7 - 50) ]

[ S =The sum of an arithmetic sequence can be found using the formula:

[ S_n = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S_n ) is the sum of the first ( n ) terms,
- ( a_1 ) is the first term of the sequence,
- ( a_n ) is the ( n )-th term of the sequence,
- ( n ) is the number of terms in the sequence.

Given: ( a_1 = 7 ) (first term) ( d = -3 ) (common difference) ( n = 20 ) (number of terms)

[ a_n = a_1 + (n - 1)d ]

[ a_n = 7 + (20 - 1)(-3) ]

[ a_n = 7 + 19(-3) ]

[ a_n = 7 - 57 ]

[ a_n = -50 ]

Now, substitute the values of ( a_1 ) and ( a_n ) into the sum formula:

[ S_{20} = \frac{20}{2}(7 + (-50))The sum ( S ) of an arithmetic sequence can be found using the formula:

[ S = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S ) is the sum of the sequence
- ( n ) is the number of terms
- ( a_1 ) is the first term
- ( a_n ) is the ( n )th term

Given:

- ( a_1 = 7 )
- ( d = -3 ) (common difference)
- ( n = 20 )

[ a_n = a_1 + (n - 1)d ]

Substitute the given values:

[ a_n = 7 + (20 - 1)(-3) ]

[ a_n = 7 + 19(-3) ]

[ a_n = 7 - 57 ]

[ a_n = -50 ]

Now, substitute ( a_1 = 7 ), ( a_n = -50 ), and ( n = 20 ) into the sum formula:

[ S = \frac{20}{2}(7 - 50) ]

[ S = 10The sum of an arithmetic sequence can be found using the formula:

[ S_n = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S_n ) is the sum of the first ( n ) terms,
- ( a_1 ) is the first term of the sequence,
- ( a_n ) is the ( n )-th term of the sequence,
- ( n ) is the number of terms in the sequence.

Given: ( a_1 = 7 ) (first term) ( d = -3 ) (common difference) ( n = 20 ) (number of terms)

[ a_n = a_1 + (n - 1)d ]

[ a_n = 7 + (20 - 1)(-3) ]

[ a_n = 7 + 19(-3) ]

[ a_n = 7 - 57 ]

[ a_n = -50 ]

Now, substitute the values of ( a_1 ) and ( a_n ) into the sum formula:

[ S_{20} = \frac{20}{2}(7 + (-50)) ]

The sum ( S ) of an arithmetic sequence can be found using the formula:

[ S = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S ) is the sum of the sequence
- ( n ) is the number of terms
- ( a_1 ) is the first term
- ( a_n ) is the ( n )th term

Given:

- ( a_1 = 7 )
- ( d = -3 ) (common difference)
- ( n = 20 )

[ a_n = a_1 + (n - 1)d ]

Substitute the given values:

[ a_n = 7 + (20 - 1)(-3) ]

[ a_n = 7 + 19(-3) ]

[ a_n = 7 - 57 ]

[ a_n = -50 ]

Now, substitute ( a_1 = 7 ), ( a_n = -50 ), and ( n = 20 ) into the sum formula:

[ S = \frac{20}{2}(7 - 50) ]

[ S = 10(-The sum of an arithmetic sequence can be found using the formula:

[ S_n = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S_n ) is the sum of the first ( n ) terms,
- ( a_1 ) is the first term of the sequence,
- ( a_n ) is the ( n )-th term of the sequence,
- ( n ) is the number of terms in the sequence.

Given: ( a_1 = 7 ) (first term) ( d = -3 ) (common difference) ( n = 20 ) (number of terms)

[ a_n = a_1 + (n - 1)d ]

[ a_n = 7 + (20 - 1)(-3) ]

[ a_n = 7 + 19(-3) ]

[ a_n = 7 - 57 ]

[ a_n = -50 ]

Now, substitute the values of ( a_1 ) and ( a_n ) into the sum formula:

[ S_{20} = \frac{20}{2}(7 + (-50)) ]

[The sum ( S ) of an arithmetic sequence can be found using the formula:

[ S = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S ) is the sum of the sequence
- ( n ) is the number of terms
- ( a_1 ) is the first term
- ( a_n ) is the ( n )th term

Given:

- ( a_1 = 7 )
- ( d = -3 ) (common difference)
- ( n = 20 )

[ a_n = a_1 + (n - 1)d ]

Substitute the given values:

[ a_n = 7 + (20 - 1)(-3) ]

[ a_n = 7 + 19(-3) ]

[ a_n = 7 - 57 ]

[ a_n = -50 ]

Now, substitute ( a_1 = 7 ), ( a_n = -50 ), and ( n = 20 ) into the sum formula:

[ S = \frac{20}{2}(7 - 50) ]

[ S = 10(-43The sum of an arithmetic sequence can be found using the formula:

[ S_n = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S_n ) is the sum of the first ( n ) terms,
- ( a_1 ) is the first term of the sequence,
- ( a_n ) is the ( n )-th term of the sequence,
- ( n ) is the number of terms in the sequence.

Given: ( a_1 = 7 ) (first term) ( d = -3 ) (common difference) ( n = 20 ) (number of terms)

[ a_n = a_1 + (n - 1)d ]

[ a_n = 7 + (20 - 1)(-3) ]

[ a_n = 7 + 19(-3) ]

[ a_n = 7 - 57 ]

[ a_n = -50 ]

Now, substitute the values of ( a_1 ) and ( a_n ) into the sum formula:

[ S_{20} = \frac{20}{2}(7 + (-50)) ]

[ S_{20The sum ( S ) of an arithmetic sequence can be found using the formula:

[ S = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S ) is the sum of the sequence
- ( n ) is the number of terms
- ( a_1 ) is the first term
- ( a_n ) is the ( n )th term

Given:

- ( a_1 = 7 )
- ( d = -3 ) (common difference)
- ( n = 20 )

[ a_n = a_1 + (n - 1)d ]

Substitute the given values:

[ a_n = 7 + (20 - 1)(-3) ]

[ a_n = 7 + 19(-3) ]

[ a_n = 7 - 57 ]

[ a_n = -50 ]

Now, substitute ( a_1 = 7 ), ( a_n = -50 ), and ( n = 20 ) into the sum formula:

[ S = \frac{20}{2}(7 - 50) ]

[ S = 10(-43)The sum of an arithmetic sequence can be found using the formula:

[ S_n = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S_n ) is the sum of the first ( n ) terms,
- ( a_1 ) is the first term of the sequence,
- ( a_n ) is the ( n )-th term of the sequence,
- ( n ) is the number of terms in the sequence.

Given: ( a_1 = 7 ) (first term) ( d = -3 ) (common difference) ( n = 20 ) (number of terms)

[ a_n = a_1 + (n - 1)d ]

[ a_n = 7 + (20 - 1)(-3) ]

[ a_n = 7 + 19(-3) ]

[ a_n = 7 - 57 ]

[ a_n = -50 ]

Now, substitute the values of ( a_1 ) and ( a_n ) into the sum formula:

[ S_{20} = \frac{20}{2}(7 + (-50)) ]

[ S_{20}The sum ( S ) of an arithmetic sequence can be found using the formula:

[ S = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S ) is the sum of the sequence
- ( n ) is the number of terms
- ( a_1 ) is the first term
- ( a_n ) is the ( n )th term

Given:

- ( a_1 = 7 )
- ( d = -3 ) (common difference)
- ( n = 20 )

[ a_n = a_1 + (n - 1)d ]

Substitute the given values:

[ a_n = 7 + (20 - 1)(-3) ]

[ a_n = 7 + 19(-3) ]

[ a_n = 7 - 57 ]

[ a_n = -50 ]

Now, substitute ( a_1 = 7 ), ( a_n = -50 ), and ( n = 20 ) into the sum formula:

[ S = \frac{20}{2}(7 - 50) ]

[ S = 10(-43) \The sum of an arithmetic sequence can be found using the formula:

[ S_n = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S_n ) is the sum of the first ( n ) terms,
- ( a_1 ) is the first term of the sequence,
- ( a_n ) is the ( n )-th term of the sequence,
- ( n ) is the number of terms in the sequence.

Given: ( a_1 = 7 ) (first term) ( d = -3 ) (common difference) ( n = 20 ) (number of terms)

[ a_n = a_1 + (n - 1)d ]

[ a_n = 7 + (20 - 1)(-3) ]

[ a_n = 7 + 19(-3) ]

[ a_n = 7 - 57 ]

[ a_n = -50 ]

Now, substitute the values of ( a_1 ) and ( a_n ) into the sum formula:

[ S_{20} = \frac{20}{2}(7 + (-50)) ]

[ S_{20} = \The sum ( S ) of an arithmetic sequence can be found using the formula:

[ S = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S ) is the sum of the sequence
- ( n ) is the number of terms
- ( a_1 ) is the first term
- ( a_n ) is the ( n )th term

Given:

- ( a_1 = 7 )
- ( d = -3 ) (common difference)
- ( n = 20 )

[ a_n = a_1 + (n - 1)d ]

Substitute the given values:

[ a_n = 7 + (20 - 1)(-3) ]

[ a_n = 7 + 19(-3) ]

[ a_n = 7 - 57 ]

[ a_n = -50 ]

Now, substitute ( a_1 = 7 ), ( a_n = -50 ), and ( n = 20 ) into the sum formula:

[ S = \frac{20}{2}(7 - 50) ]

[ S = 10(-43) ]

The sum of an arithmetic sequence can be found using the formula:

[ S_n = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S_n ) is the sum of the first ( n ) terms,
- ( a_1 ) is the first term of the sequence,
- ( a_n ) is the ( n )-th term of the sequence,
- ( n ) is the number of terms in the sequence.

Given: ( a_1 = 7 ) (first term) ( d = -3 ) (common difference) ( n = 20 ) (number of terms)

[ a_n = a_1 + (n - 1)d ]

[ a_n = 7 + (20 - 1)(-3) ]

[ a_n = 7 + 19(-3) ]

[ a_n = 7 - 57 ]

[ a_n = -50 ]

Now, substitute the values of ( a_1 ) and ( a_n ) into the sum formula:

[ S_{20} = \frac{20}{2}(7 + (-50)) ]

[ S_{20} = \fracThe sum ( S ) of an arithmetic sequence can be found using the formula:

[ S = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S ) is the sum of the sequence
- ( n ) is the number of terms
- ( a_1 ) is the first term
- ( a_n ) is the ( n )th term

Given:

- ( a_1 = 7 )
- ( d = -3 ) (common difference)
- ( n = 20 )

[ a_n = a_1 + (n - 1)d ]

Substitute the given values:

[ a_n = 7 + (20 - 1)(-3) ]

[ a_n = 7 + 19(-3) ]

[ a_n = 7 - 57 ]

[ a_n = -50 ]

Now, substitute ( a_1 = 7 ), ( a_n = -50 ), and ( n = 20 ) into the sum formula:

[ S = \frac{20}{2}(7 - 50) ]

[ S = 10(-43) ]

[The sum of an arithmetic sequence can be found using the formula:

[ S_n = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S_n ) is the sum of the first ( n ) terms,
- ( a_1 ) is the first term of the sequence,
- ( a_n ) is the ( n )-th term of the sequence,
- ( n ) is the number of terms in the sequence.

Given: ( a_1 = 7 ) (first term) ( d = -3 ) (common difference) ( n = 20 ) (number of terms)

[ a_n = a_1 + (n - 1)d ]

[ a_n = 7 + (20 - 1)(-3) ]

[ a_n = 7 + 19(-3) ]

[ a_n = 7 - 57 ]

[ a_n = -50 ]

Now, substitute the values of ( a_1 ) and ( a_n ) into the sum formula:

[ S_{20} = \frac{20}{2}(7 + (-50)) ]

[ S_{20} = \frac{20The sum ( S ) of an arithmetic sequence can be found using the formula:

[ S = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S ) is the sum of the sequence
- ( n ) is the number of terms
- ( a_1 ) is the first term
- ( a_n ) is the ( n )th term

Given:

- ( a_1 = 7 )
- ( d = -3 ) (common difference)
- ( n = 20 )

[ a_n = a_1 + (n - 1)d ]

Substitute the given values:

[ a_n = 7 + (20 - 1)(-3) ]

[ a_n = 7 + 19(-3) ]

[ a_n = 7 - 57 ]

[ a_n = -50 ]

Now, substitute ( a_1 = 7 ), ( a_n = -50 ), and ( n = 20 ) into the sum formula:

[ S = \frac{20}{2}(7 - 50) ]

[ S = 10(-43) ]

[ SThe sum of an arithmetic sequence can be found using the formula:

[ S_n = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S_n ) is the sum of the first ( n ) terms,
- ( a_1 ) is the first term of the sequence,
- ( a_n ) is the ( n )-th term of the sequence,
- ( n ) is the number of terms in the sequence.

Given: ( a_1 = 7 ) (first term) ( d = -3 ) (common difference) ( n = 20 ) (number of terms)

[ a_n = a_1 + (n - 1)d ]

[ a_n = 7 + (20 - 1)(-3) ]

[ a_n = 7 + 19(-3) ]

[ a_n = 7 - 57 ]

[ a_n = -50 ]

Now, substitute the values of ( a_1 ) and ( a_n ) into the sum formula:

[ S_{20} = \frac{20}{2}(7 + (-50)) ]

[ S_{20} = \frac{20}{The sum ( S ) of an arithmetic sequence can be found using the formula:

[ S = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S ) is the sum of the sequence
- ( n ) is the number of terms
- ( a_1 ) is the first term
- ( a_n ) is the ( n )th term

Given:

- ( a_1 = 7 )
- ( d = -3 ) (common difference)
- ( n = 20 )

[ a_n = a_1 + (n - 1)d ]

Substitute the given values:

[ a_n = 7 + (20 - 1)(-3) ]

[ a_n = 7 + 19(-3) ]

[ a_n = 7 - 57 ]

[ a_n = -50 ]

Now, substitute ( a_1 = 7 ), ( a_n = -50 ), and ( n = 20 ) into the sum formula:

[ S = \frac{20}{2}(7 - 50) ]

[ S = 10(-43) ]

[ S =The sum of an arithmetic sequence can be found using the formula:

[ S_n = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S_n ) is the sum of the first ( n ) terms,
- ( a_1 ) is the first term of the sequence,
- ( a_n ) is the ( n )-th term of the sequence,
- ( n ) is the number of terms in the sequence.

Given: ( a_1 = 7 ) (first term) ( d = -3 ) (common difference) ( n = 20 ) (number of terms)

[ a_n = a_1 + (n - 1)d ]

[ a_n = 7 + (20 - 1)(-3) ]

[ a_n = 7 + 19(-3) ]

[ a_n = 7 - 57 ]

[ a_n = -50 ]

Now, substitute the values of ( a_1 ) and ( a_n ) into the sum formula:

[ S_{20} = \frac{20}{2}(7 + (-50)) ]

[ S_{20} = \frac{20}{2The sum ( S ) of an arithmetic sequence can be found using the formula:

[ S = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S ) is the sum of the sequence
- ( n ) is the number of terms
- ( a_1 ) is the first term
- ( a_n ) is the ( n )th term

Given:

- ( a_1 = 7 )
- ( d = -3 ) (common difference)
- ( n = 20 )

[ a_n = a_1 + (n - 1)d ]

Substitute the given values:

[ a_n = 7 + (20 - 1)(-3) ]

[ a_n = 7 + 19(-3) ]

[ a_n = 7 - 57 ]

[ a_n = -50 ]

Now, substitute ( a_1 = 7 ), ( a_n = -50 ), and ( n = 20 ) into the sum formula:

[ S = \frac{20}{2}(7 - 50) ]

[ S = 10(-43) ]

[ S = -The sum of an arithmetic sequence can be found using the formula:

[ S_n = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S_n ) is the sum of the first ( n ) terms,
- ( a_1 ) is the first term of the sequence,
- ( a_n ) is the ( n )-th term of the sequence,
- ( n ) is the number of terms in the sequence.

Given: ( a_1 = 7 ) (first term) ( d = -3 ) (common difference) ( n = 20 ) (number of terms)

[ a_n = a_1 + (n - 1)d ]

[ a_n = 7 + (20 - 1)(-3) ]

[ a_n = 7 + 19(-3) ]

[ a_n = 7 - 57 ]

[ a_n = -50 ]

Now, substitute the values of ( a_1 ) and ( a_n ) into the sum formula:

[ S_{20} = \frac{20}{2}(7 + (-50)) ]

[ S_{20} = \frac{20}{2}(The sum ( S ) of an arithmetic sequence can be found using the formula:

[ S = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S ) is the sum of the sequence
- ( n ) is the number of terms
- ( a_1 ) is the first term
- ( a_n ) is the ( n )th term

Given:

- ( a_1 = 7 )
- ( d = -3 ) (common difference)
- ( n = 20 )

[ a_n = a_1 + (n - 1)d ]

Substitute the given values:

[ a_n = 7 + (20 - 1)(-3) ]

[ a_n = 7 + 19(-3) ]

[ a_n = 7 - 57 ]

[ a_n = -50 ]

Now, substitute ( a_1 = 7 ), ( a_n = -50 ), and ( n = 20 ) into the sum formula:

[ S = \frac{20}{2}(7 - 50) ]

[ S = 10(-43) ]

[ S = -430 ]

The sum of an arithmetic sequence can be found using the formula:

[ S_n = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S_n ) is the sum of the first ( n ) terms,
- ( a_1 ) is the first term of the sequence,
- ( a_n ) is the ( n )-th term of the sequence,
- ( n ) is the number of terms in the sequence.

Given: ( a_1 = 7 ) (first term) ( d = -3 ) (common difference) ( n = 20 ) (number of terms)

[ a_n = a_1 + (n - 1)d ]

[ a_n = 7 + (20 - 1)(-3) ]

[ a_n = 7 + 19(-3) ]

[ a_n = 7 - 57 ]

[ a_n = -50 ]

Now, substitute the values of ( a_1 ) and ( a_n ) into the sum formula:

[ S_{20} = \frac{20}{2}(7 + (-50)) ]

[ S_{20} = \frac{20}{2}(7The sum ( S ) of an arithmetic sequence can be found using the formula:

[ S = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S ) is the sum of the sequence
- ( n ) is the number of terms
- ( a_1 ) is the first term
- ( a_n ) is the ( n )th term

Given:

- ( a_1 = 7 )
- ( d = -3 ) (common difference)
- ( n = 20 )

[ a_n = a_1 + (n - 1)d ]

Substitute the given values:

[ a_n = 7 + (20 - 1)(-3) ]

[ a_n = 7 + 19(-3) ]

[ a_n = 7 - 57 ]

[ a_n = -50 ]

Now, substitute ( a_1 = 7 ), ( a_n = -50 ), and ( n = 20 ) into the sum formula:

[ S = \frac{20}{2}(7 - 50) ]

[ S = 10(-43) ]

[ S = -430 ]

ThereforeThe sum of an arithmetic sequence can be found using the formula:

[ S_n = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S_n ) is the sum of the first ( n ) terms,
- ( a_1 ) is the first term of the sequence,
- ( a_n ) is the ( n )-th term of the sequence,
- ( n ) is the number of terms in the sequence.

Given: ( a_1 = 7 ) (first term) ( d = -3 ) (common difference) ( n = 20 ) (number of terms)

[ a_n = a_1 + (n - 1)d ]

[ a_n = 7 + (20 - 1)(-3) ]

[ a_n = 7 + 19(-3) ]

[ a_n = 7 - 57 ]

[ a_n = -50 ]

Now, substitute the values of ( a_1 ) and ( a_n ) into the sum formula:

[ S_{20} = \frac{20}{2}(7 + (-50)) ]

[ S_{20} = \frac{20}{2}(7 - The sum ( S ) of an arithmetic sequence can be found using the formula:

[ S = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S ) is the sum of the sequence
- ( n ) is the number of terms
- ( a_1 ) is the first term
- ( a_n ) is the ( n )th term

Given:

- ( a_1 = 7 )
- ( d = -3 ) (common difference)
- ( n = 20 )

[ a_n = a_1 + (n - 1)d ]

Substitute the given values:

[ a_n = 7 + (20 - 1)(-3) ]

[ a_n = 7 + 19(-3) ]

[ a_n = 7 - 57 ]

[ a_n = -50 ]

Now, substitute ( a_1 = 7 ), ( a_n = -50 ), and ( n = 20 ) into the sum formula:

[ S = \frac{20}{2}(7 - 50) ]

[ S = 10(-43) ]

[ S = -430 ]

Therefore, theThe sum of an arithmetic sequence can be found using the formula:

[ S_n = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S_n ) is the sum of the first ( n ) terms,
- ( a_1 ) is the first term of the sequence,
- ( a_n ) is the ( n )-th term of the sequence,
- ( n ) is the number of terms in the sequence.

Given: ( a_1 = 7 ) (first term) ( d = -3 ) (common difference) ( n = 20 ) (number of terms)

[ a_n = a_1 + (n - 1)d ]

[ a_n = 7 + (20 - 1)(-3) ]

[ a_n = 7 + 19(-3) ]

[ a_n = 7 - 57 ]

[ a_n = -50 ]

Now, substitute the values of ( a_1 ) and ( a_n ) into the sum formula:

[ S_{20} = \frac{20}{2}(7 + (-50)) ]

[ S_{20} = \frac{20}{2}(7 - 50The sum ( S ) of an arithmetic sequence can be found using the formula:

[ S = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S ) is the sum of the sequence
- ( n ) is the number of terms
- ( a_1 ) is the first term
- ( a_n ) is the ( n )th term

Given:

- ( a_1 = 7 )
- ( d = -3 ) (common difference)
- ( n = 20 )

[ a_n = a_1 + (n - 1)d ]

Substitute the given values:

[ a_n = 7 + (20 - 1)(-3) ]

[ a_n = 7 + 19(-3) ]

[ a_n = 7 - 57 ]

[ a_n = -50 ]

Now, substitute ( a_1 = 7 ), ( a_n = -50 ), and ( n = 20 ) into the sum formula:

[ S = \frac{20}{2}(7 - 50) ]

[ S = 10(-43) ]

[ S = -430 ]

Therefore, the sumThe sum of an arithmetic sequence can be found using the formula:

[ S_n = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S_n ) is the sum of the first ( n ) terms,
- ( a_1 ) is the first term of the sequence,
- ( a_n ) is the ( n )-th term of the sequence,
- ( n ) is the number of terms in the sequence.

Given: ( a_1 = 7 ) (first term) ( d = -3 ) (common difference) ( n = 20 ) (number of terms)

[ a_n = a_1 + (n - 1)d ]

[ a_n = 7 + (20 - 1)(-3) ]

[ a_n = 7 + 19(-3) ]

[ a_n = 7 - 57 ]

[ a_n = -50 ]

Now, substitute the values of ( a_1 ) and ( a_n ) into the sum formula:

[ S_{20} = \frac{20}{2}(7 + (-50)) ]

[ S_{20} = \frac{20}{2}(7 - 50)The sum ( S ) of an arithmetic sequence can be found using the formula:

[ S = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S ) is the sum of the sequence
- ( n ) is the number of terms
- ( a_1 ) is the first term
- ( a_n ) is the ( n )th term

Given:

- ( a_1 = 7 )
- ( d = -3 ) (common difference)
- ( n = 20 )

[ a_n = a_1 + (n - 1)d ]

Substitute the given values:

[ a_n = 7 + (20 - 1)(-3) ]

[ a_n = 7 + 19(-3) ]

[ a_n = 7 - 57 ]

[ a_n = -50 ]

Now, substitute ( a_1 = 7 ), ( a_n = -50 ), and ( n = 20 ) into the sum formula:

[ S = \frac{20}{2}(7 - 50) ]

[ S = 10(-43) ]

[ S = -430 ]

Therefore, the sum ofThe sum of an arithmetic sequence can be found using the formula:

[ S_n = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S_n ) is the sum of the first ( n ) terms,
- ( a_1 ) is the first term of the sequence,
- ( a_n ) is the ( n )-th term of the sequence,
- ( n ) is the number of terms in the sequence.

Given: ( a_1 = 7 ) (first term) ( d = -3 ) (common difference) ( n = 20 ) (number of terms)

[ a_n = a_1 + (n - 1)d ]

[ a_n = 7 + (20 - 1)(-3) ]

[ a_n = 7 + 19(-3) ]

[ a_n = 7 - 57 ]

[ a_n = -50 ]

Now, substitute the values of ( a_1 ) and ( a_n ) into the sum formula:

[ S_{20} = \frac{20}{2}(7 + (-50)) ]

[ S_{20} = \frac{20}{2}(7 - 50) \The sum ( S ) of an arithmetic sequence can be found using the formula:

[ S = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S ) is the sum of the sequence
- ( n ) is the number of terms
- ( a_1 ) is the first term
- ( a_n ) is the ( n )th term

Given:

- ( a_1 = 7 )
- ( d = -3 ) (common difference)
- ( n = 20 )

[ a_n = a_1 + (n - 1)d ]

Substitute the given values:

[ a_n = 7 + (20 - 1)(-3) ]

[ a_n = 7 + 19(-3) ]

[ a_n = 7 - 57 ]

[ a_n = -50 ]

Now, substitute ( a_1 = 7 ), ( a_n = -50 ), and ( n = 20 ) into the sum formula:

[ S = \frac{20}{2}(7 - 50) ]

[ S = 10(-43) ]

[ S = -430 ]

Therefore, the sum of theThe sum of an arithmetic sequence can be found using the formula:

[ S_n = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S_n ) is the sum of the first ( n ) terms,
- ( a_1 ) is the first term of the sequence,
- ( a_n ) is the ( n )-th term of the sequence,
- ( n ) is the number of terms in the sequence.

Given: ( a_1 = 7 ) (first term) ( d = -3 ) (common difference) ( n = 20 ) (number of terms)

[ a_n = a_1 + (n - 1)d ]

[ a_n = 7 + (20 - 1)(-3) ]

[ a_n = 7 + 19(-3) ]

[ a_n = 7 - 57 ]

[ a_n = -50 ]

Now, substitute the values of ( a_1 ) and ( a_n ) into the sum formula:

[ S_{20} = \frac{20}{2}(7 + (-50)) ]

[ S_{20} = \frac{20}{2}(7 - 50) ]

The sum ( S ) of an arithmetic sequence can be found using the formula:

[ S = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S ) is the sum of the sequence
- ( n ) is the number of terms
- ( a_1 ) is the first term
- ( a_n ) is the ( n )th term

Given:

- ( a_1 = 7 )
- ( d = -3 ) (common difference)
- ( n = 20 )

[ a_n = a_1 + (n - 1)d ]

Substitute the given values:

[ a_n = 7 + (20 - 1)(-3) ]

[ a_n = 7 + 19(-3) ]

[ a_n = 7 - 57 ]

[ a_n = -50 ]

Now, substitute ( a_1 = 7 ), ( a_n = -50 ), and ( n = 20 ) into the sum formula:

[ S = \frac{20}{2}(7 - 50) ]

[ S = 10(-43) ]

[ S = -430 ]

Therefore, the sum of the arithmeticThe sum of an arithmetic sequence can be found using the formula:

[ S_n = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S_n ) is the sum of the first ( n ) terms,
- ( a_1 ) is the first term of the sequence,
- ( a_n ) is the ( n )-th term of the sequence,
- ( n ) is the number of terms in the sequence.

Given: ( a_1 = 7 ) (first term) ( d = -3 ) (common difference) ( n = 20 ) (number of terms)

[ a_n = a_1 + (n - 1)d ]

[ a_n = 7 + (20 - 1)(-3) ]

[ a_n = 7 + 19(-3) ]

[ a_n = 7 - 57 ]

[ a_n = -50 ]

Now, substitute the values of ( a_1 ) and ( a_n ) into the sum formula:

[ S_{20} = \frac{20}{2}(7 + (-50)) ]

[ S_{20} = \frac{20}{2}(7 - 50) ]

[The sum ( S ) of an arithmetic sequence can be found using the formula:

[ S = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S ) is the sum of the sequence
- ( n ) is the number of terms
- ( a_1 ) is the first term
- ( a_n ) is the ( n )th term

Given:

- ( a_1 = 7 )
- ( d = -3 ) (common difference)
- ( n = 20 )

[ a_n = a_1 + (n - 1)d ]

Substitute the given values:

[ a_n = 7 + (20 - 1)(-3) ]

[ a_n = 7 + 19(-3) ]

[ a_n = 7 - 57 ]

[ a_n = -50 ]

Now, substitute ( a_1 = 7 ), ( a_n = -50 ), and ( n = 20 ) into the sum formula:

[ S = \frac{20}{2}(7 - 50) ]

[ S = 10(-43) ]

[ S = -430 ]

Therefore, the sum of the arithmetic sequenceThe sum of an arithmetic sequence can be found using the formula:

[ S_n = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S_n ) is the sum of the first ( n ) terms,
- ( a_1 ) is the first term of the sequence,
- ( a_n ) is the ( n )-th term of the sequence,
- ( n ) is the number of terms in the sequence.

Given: ( a_1 = 7 ) (first term) ( d = -3 ) (common difference) ( n = 20 ) (number of terms)

[ a_n = a_1 + (n - 1)d ]

[ a_n = 7 + (20 - 1)(-3) ]

[ a_n = 7 + 19(-3) ]

[ a_n = 7 - 57 ]

[ a_n = -50 ]

Now, substitute the values of ( a_1 ) and ( a_n ) into the sum formula:

[ S_{20} = \frac{20}{2}(7 + (-50)) ]

[ S_{20} = \frac{20}{2}(7 - 50) ]

[ SThe sum ( S ) of an arithmetic sequence can be found using the formula:

[ S = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S ) is the sum of the sequence
- ( n ) is the number of terms
- ( a_1 ) is the first term
- ( a_n ) is the ( n )th term

Given:

- ( a_1 = 7 )
- ( d = -3 ) (common difference)
- ( n = 20 )

[ a_n = a_1 + (n - 1)d ]

Substitute the given values:

[ a_n = 7 + (20 - 1)(-3) ]

[ a_n = 7 + 19(-3) ]

[ a_n = 7 - 57 ]

[ a_n = -50 ]

Now, substitute ( a_1 = 7 ), ( a_n = -50 ), and ( n = 20 ) into the sum formula:

[ S = \frac{20}{2}(7 - 50) ]

[ S = 10(-43) ]

[ S = -430 ]

Therefore, the sum of the arithmetic sequence isThe sum of an arithmetic sequence can be found using the formula:

[ S_n = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S_n ) is the sum of the first ( n ) terms,
- ( a_1 ) is the first term of the sequence,
- ( a_n ) is the ( n )-th term of the sequence,
- ( n ) is the number of terms in the sequence.

Given: ( a_1 = 7 ) (first term) ( d = -3 ) (common difference) ( n = 20 ) (number of terms)

[ a_n = a_1 + (n - 1)d ]

[ a_n = 7 + (20 - 1)(-3) ]

[ a_n = 7 + 19(-3) ]

[ a_n = 7 - 57 ]

[ a_n = -50 ]

Now, substitute the values of ( a_1 ) and ( a_n ) into the sum formula:

[ S_{20} = \frac{20}{2}(7 + (-50)) ]

[ S_{20} = \frac{20}{2}(7 - 50) ]

[ S_{The sum ( S ) of an arithmetic sequence can be found using the formula:

[ S = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S ) is the sum of the sequence
- ( n ) is the number of terms
- ( a_1 ) is the first term
- ( a_n ) is the ( n )th term

Given:

- ( a_1 = 7 )
- ( d = -3 ) (common difference)
- ( n = 20 )

[ a_n = a_1 + (n - 1)d ]

Substitute the given values:

[ a_n = 7 + (20 - 1)(-3) ]

[ a_n = 7 + 19(-3) ]

[ a_n = 7 - 57 ]

[ a_n = -50 ]

Now, substitute ( a_1 = 7 ), ( a_n = -50 ), and ( n = 20 ) into the sum formula:

[ S = \frac{20}{2}(7 - 50) ]

[ S = 10(-43) ]

[ S = -430 ]

Therefore, the sum of the arithmetic sequence is -430The sum of an arithmetic sequence can be found using the formula:

[ S_n = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S_n ) is the sum of the first ( n ) terms,
- ( a_1 ) is the first term of the sequence,
- ( a_n ) is the ( n )-th term of the sequence,
- ( n ) is the number of terms in the sequence.

Given: ( a_1 = 7 ) (first term) ( d = -3 ) (common difference) ( n = 20 ) (number of terms)

[ a_n = a_1 + (n - 1)d ]

[ a_n = 7 + (20 - 1)(-3) ]

[ a_n = 7 + 19(-3) ]

[ a_n = 7 - 57 ]

[ a_n = -50 ]

Now, substitute the values of ( a_1 ) and ( a_n ) into the sum formula:

[ S_{20} = \frac{20}{2}(7 + (-50)) ]

[ S_{20} = \frac{20}{2}(7 - 50) ]

[ S_{20}The sum ( S ) of an arithmetic sequence can be found using the formula:

[ S = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S ) is the sum of the sequence
- ( n ) is the number of terms
- ( a_1 ) is the first term
- ( a_n ) is the ( n )th term

Given:

- ( a_1 = 7 )
- ( d = -3 ) (common difference)
- ( n = 20 )

[ a_n = a_1 + (n - 1)d ]

Substitute the given values:

[ a_n = 7 + (20 - 1)(-3) ]

[ a_n = 7 + 19(-3) ]

[ a_n = 7 - 57 ]

[ a_n = -50 ]

Now, substitute ( a_1 = 7 ), ( a_n = -50 ), and ( n = 20 ) into the sum formula:

[ S = \frac{20}{2}(7 - 50) ]

[ S = 10(-43) ]

[ S = -430 ]

Therefore, the sum of the arithmetic sequence is -430.The sum of an arithmetic sequence can be found using the formula:

[ S_n = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S_n ) is the sum of the first ( n ) terms,
- ( a_1 ) is the first term of the sequence,
- ( a_n ) is the ( n )-th term of the sequence,
- ( n ) is the number of terms in the sequence.

Given: ( a_1 = 7 ) (first term) ( d = -3 ) (common difference) ( n = 20 ) (number of terms)

[ a_n = a_1 + (n - 1)d ]

[ a_n = 7 + (20 - 1)(-3) ]

[ a_n = 7 + 19(-3) ]

[ a_n = 7 - 57 ]

[ a_n = -50 ]

Now, substitute the values of ( a_1 ) and ( a_n ) into the sum formula:

[ S_{20} = \frac{20}{2}(7 + (-50)) ]

[ S_{20} = \frac{20}{2}(7 - 50) ]

[ S_{20} =The sum ( S ) of an arithmetic sequence can be found using the formula:

[ S = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S ) is the sum of the sequence
- ( n ) is the number of terms
- ( a_1 ) is the first term
- ( a_n ) is the ( n )th term

Given:

- ( a_1 = 7 )
- ( d = -3 ) (common difference)
- ( n = 20 )

[ a_n = a_1 + (n - 1)d ]

Substitute the given values:

[ a_n = 7 + (20 - 1)(-3) ]

[ a_n = 7 + 19(-3) ]

[ a_n = 7 - 57 ]

[ a_n = -50 ]

Now, substitute ( a_1 = 7 ), ( a_n = -50 ), and ( n = 20 ) into the sum formula:

[ S = \frac{20}{2}(7 - 50) ]

[ S = 10(-43) ]

[ S = -430 ]

Therefore, the sum of the arithmetic sequence is -430.The sum of an arithmetic sequence can be found using the formula:

[ S_n = \frac{n}{2}(a_1 + a_n) ]

where:

- ( S_n ) is the sum of the first ( n ) terms,
- ( a_1 ) is the first term of the sequence,
- ( a_n ) is the ( n )-th term of the sequence,
- ( n ) is the number of terms in the sequence.

Given: ( a_1 = 7 ) (first term) ( d = -3 ) (common difference) ( n = 20 ) (number of terms)

[ a_n = a_1 + (n - 1)d ]

[ a_n = 7 + (20 - 1)(-3) ]

[ a_n = 7 + 19(-3) ]

[ a_n = 7 - 57 ]

[ a_n = -50 ]

Now, substitute the values of ( a_1 ) and ( a_n ) into the sum formula:

[ S_{20} = \frac{20}{2}(7 + (-50)) ]

[ S_{20} = \frac{20}{2}(7 - 50) ]

[ S_{20} = \frac{20}{2}(-43) ]

[ S_{20} = 10(-43) ]

[ S_{20} = -430 ]

Therefore, the sum of the arithmetic sequence is -430.

By signing up, you agree to our Terms of Service and Privacy Policy

When evaluating a one-sided limit, you need to be careful when a quantity is approaching zero since its sign is different depending on which way it is approaching zero from. Let us look at some examples.

When evaluating a one-sided limit, you need to be careful when a quantity is approaching zero since its sign is different depending on which way it is approaching zero from. Let us look at some examples.

When evaluating a one-sided limit, you need to be careful when a quantity is approaching zero since its sign is different depending on which way it is approaching zero from. Let us look at some examples.

- How do you write the nth term rule for the sequence #4,1,-2,-5,-8,...#?
- Given the first term and the common difference of an arithmetic sequence how do you find the first five terms and explicit formula: a1 = 28, d=10?
- What is a possible explicit rule for the nth term of the sequence: #25, 15, 5, -5, -15#?
- How do you find the first five terms in the geometric sequence which is such that the sum of the 1st and 3rd terms is 50, and the sum of the 2nd and 4th terms is 150?
- How do you write the first five terms of the arithmetic sequence given #a_1=2, a_12=46#?

- 98% accuracy study help
- Covers math, physics, chemistry, biology, and more
- Step-by-step, in-depth guides
- Readily available 24/7