How do you define a variable and write an expression for each phrase: the sum of 13 and twice a number?

Answer 1

2x + 13

The reason for this is because, well, you kinda gotta go backwards. Twice an unknown number, and unknown number being a variable (by definition) would leave it as x, and twice of x is 2x.

And to finish off, since it's the sum with 13, and since sum means addition, it would end it with 2x + 13.

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Answer 2

Julia Adams

A variable is something that can change and/or is unknown.

sum = + or addition a number = a variable or unknown value. twice = # 2 xx# or multiply by 2 13 = 13

(2n) = twice the unknown number

# ( 13 + 2n) # is the algebraic expression for the phase

the sum of thirteen and w twice a number

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Answer 3

Eva Adamson

To define a variable, you can use any letter or symbol to represent an unknown quantity. Let's use ( x ) to represent the unknown number.

The expression for "the sum of 13 and twice a number" would be: [ 13 + 2x ]

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Answer from HIX Tutor

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.