Originally Posted by

**Ackbeet** Well, what did you get for the derivatives in 1)?

For 2) b), you have to use the chain rule from the outside in, and you're going to have to use it twice (having done part a means you don't have to do it three times, like you normally would). Here's the first step:

$\displaystyle \displaystyle \frac{dy}{dx} = \cos\left(\left(\dfrac{3x-4}{x+7}\right)^{\!\!8}\right)\;\frac{d}{dx}\left(\ left(\dfrac{3x-4}{x+7}\right)^{\!\!8}\right).$

Thank you for the sentence clarifying what the exponent 8 applies to, but if you include extra parentheses like I've done here, you don't need to bother.

Can you keep going from here?