Question

using chain rule: y=5cos^-4x

Answer 1

You want to find derivative here ???

Answer 2

yes please.

Answer 3

Firstly tell me what is the derivative of cos(x) ???

Answer 4

-sinx

Answer 5

Yep..

Your question is :

\[y = 5\cos^{-4}(x)\]

Right ??

Answer 6

yes

Answer 7

Do you know how to find derivative when power is there??
Here power is -4 ..

Answer 8

\[\frac{d}{dx}(f^n) = n \cdot f^{n-1}\]

Answer 9

yes I know that

Answer 10

\[\frac{d}{dx}(\cos^{-4}(x)) = -4 \cdot \cos^{-5}(x) \cdot \frac{d}{dx}(\cos(x)) \cdot \frac{d}{dx}(x)\]

Answer 11

Can you go forward from here ???

Answer 12

yes, thanks

Answer 13

If problem arises, then @UnkleRhaukus and @sauravshakya will help you in going forward..

Gotta go...