Please Help! Let f(x)=(13x^3−3x+8)((3x^−2)+(2x^−3)). Evaluate f′(x) at the following points: f'(-6)

Question

solomonzelman · Answer

What is the derivative of f?

solomonzelman · Answer

(I would use the product rule, rather than expanding, but that is up to you)

solomonzelman · Answer

Tell me:

$1)$   The derivative of:   $\color{black}{ \displaystyle 13x^3−3x+8 }$   is?
$2)$   The derivative of:   $\color{black}{ \displaystyle 3x^{-2}+2x^{-3} }$   is?

anonymous · Answer

I did the product rule and the plugged in the -6 and my answer was 39.6049

solomonzelman · Answer

can you tell me what you got for the derivative of the function?

anonymous · Answer

((39x^2)-3)((3x^-2)+(2x^-3))+((13x^3)-3x+8)((-6x^-3)+(-6x^-4))

solomonzelman · Answer

yes, that is correct

solomonzelman · Answer

Now we plug in x=-6... we can use wolfram for this:)

anonymous · Answer

okay so is my answer the same?

solomonzelman · Answer

http://www.wolframalpha.com/input/?i=%2839%28-6%29%5E2-3%29%283%28-6%29%5E%28-2%29%2B2%28-6%29%5E%28-3%29%29%2B%2813%28-6%29%5E3-3%28-6%29%2B8%29%28-6%28-6%29%5E%28-3%29%2B-6%28-6%29%5E%28-4%29%29

anonymous · Answer

because whenever I type the answer into the program I am using for my homework its says it's incorrect

solomonzelman · Answer

39.3796

solomonzelman · Answer

is what wolfram gives

anonymous · Answer

attachment

solomonzelman · Answer

I honestly have no clue about what happened.
We got the correct derivative and I used the calculator for f'(-6)....

anonymous · Answer

I know .-. I've attempted this problem 15 times

solomonzelman · Answer

Yes, that is pretty strange. to me at least.

triciaal · Answer

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