What are the x-coordinates for the maximum points in the function f(x)=4cos(2x-pi) from x=0 to x=2pi

The answer to the problem is as follows:

Well isn't the range of y=cos(u) is [-1,1]

So the max value for y=cos(u) is 1
 
And the min value for y=cos(u) is -1 --

So the max value for f(x)=4cos(u) is:

f(u)=4cos(u)

I hope my answer has come to your help. God bless and have a nice day ahead!

Hello there.

What are the x-coordinates for the maximum points in the function f(x)=4cos(2x-pi) from x=0 to x=2pi

f(u)=4cos(u)

First subtract 10 from both side
y^2+6y-16=0
(y+8)(y-2)=0
-8 and 2