Question

For the following function, find the relative max's or min's using any method.
I'm having a hard time finding the critical points...

Answer 1

Sorry, I forgot to post the function:
f(x)=cos3x

Answer 2

surely you jest! The critical points are where f' = 0.

f'(x) = -3sin3x

You know that sin(u)=0 when u is a multiple of pi.
So, f'(x) = 0 when 3x is a multiple of pi:

x= 0, pi/3, 2pi/3, ...