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OpenStudy (anonymous):

Calculus help?

OpenStudy (anonymous):

\[\large f(x)=\sqrt[3]{(x^2-1)^2}\] Find f'(x) and state its domain.

OpenStudy (unklerhaukus):

\[f(x)=\sqrt[3]{(x^2-1)^2}=(x^2-1)^{2/3}\]

OpenStudy (unklerhaukus):

\[f'(x)=\frac{\text d }{\text dx}(x^2−1)^{2/3}\]

OpenStudy (unklerhaukus):

\[\frac{\text d }{\text d x}\left(f(x)^n\right)=nf^{n-1}\] \[\frac{\text d }{\text d x}\left(f \circ g\right)=f'(g)\cdot g'\]

OpenStudy (anonymous):

So\[\large f'(x)=(x^2-1)^{\frac23}+\frac23(x^2-1)^{-\frac13}(2x)x\]?

OpenStudy (unklerhaukus):

where did that plus sign come from?

OpenStudy (anonymous):

Product rule, I thought.

OpenStudy (unklerhaukus):

there is no product

OpenStudy (unklerhaukus):

i have the chain rule \((f \circ g)'\)

OpenStudy (anonymous):

Oh shoot\[\large f(x)=x \sqrt[3]{(x^2-1)^2}\]This is the correct function, sorry. I think I got the derivative, but I'm stuck in finding the domain.

OpenStudy (unklerhaukus):

well now the question has changed you almost had the right solution

OpenStudy (unklerhaukus):

using the product rule was right

OpenStudy (unklerhaukus):

and you actually had it more than almost right you have it exactly right

OpenStudy (unklerhaukus):

i cant see any numbers to exclude form the domain

OpenStudy (anonymous):

Well, I have x≠±1. But the answer sheet also says -1.4<x<1.4. I don't get that part :(

OpenStudy (unklerhaukus):

im getting x cannot be \([-1,1]\)

OpenStudy (anonymous):

That's what I have too. But that's incomplete apparently

OpenStudy (unklerhaukus):

but i mean x cannot be -1, any where in between up 1

OpenStudy (unklerhaukus):

actually it can be between. i think you are right and the answer has not got the right answer

OpenStudy (unklerhaukus):

answer sheet is wrong*

OpenStudy (anonymous):

ok thanks :) yeah maybe

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