Question

How do you use the chain rule to differentiate `-cos(4x+9)`?

Answer 1

`4sin(4x+9)`

Explanation:

Using the chain rule and let `u=4x+9`

`d/(du)(-cosu)*d/(du)(u)`

`d/(du)(-cosu)=sinu`

`d/(dx)4x+9=4`

Therefore the answer is,

`d/dx(-cos(4x+9))=4sin(4x+9)`