Q: Let f(x)=20x-10sin(4x) for 0<=x<=pi/2
Find the largest interval(s) over which the function f is increasing or decreasing.
I tried to solve this:
f'(x)=20-40cos(4x)
=20(1-2cos(4x))
on keeping f'(x)=0, i get x=pi/12
I just cannot get correct intervals to work properly with my online math homework system!
Please help me!
Thank you SO much!