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How do you evaluate #f( 15) # if #f(x)= x ^ { 3} - 6x + 4#?

Answer 1

Eli Assouline

See a solution process below:

To evaluate #f(15)# you need to substitute #color(red)(15)# for each occurrence of #color(red)(x)# in #f(x)#:

#f(color(red)(x)) = color(red)(x)^3 - 6color(red)(x) + 4# becomes:

#f(color(red)(15)) = color(red)(15)^3 - (6 xx color(red)(15)) + 4#

#f(color(red)(15)) = 3375 - 90 + 4#

#f(color(red)(15)) = 3285 + 4#

#f(color(red)(15)) = 3289#

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Answer 2

Eva Abramson

To evaluate ( f(15) ) if ( f(x) = x^3 - 6x + 4 ), substitute ( x = 15 ) into the function:

[ f(15) = (15)^3 - 6(15) + 4 ]

[ f(15) = 3375 - 90 + 4 ]

[ f(15) = 3289 ]

So, ( f(15) = 3289 ).

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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.