(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

Find f'(x) for f(x) = sin x + 2 cos^3 x

2. Relevant equations

Other than basic derivative properties and formulas, no.

3. The attempt at a solution

f'(x) = sin x + 2cos^3 x

= cos x - 6sin^2 x

The book says the answer is f'(x) = cos x - 6cos^2 x sin x however I don't understand where the sin x comes from... any help?

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# A simple derivative that I'm messing up on

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