Using the “completing the square” technique, the maximum value of the function f(x)=sin^2(2x)-2cos^2x is (A) −1/4 (B) 1/4 (C) −1/2 (D) 1/2

With Jishka's non-functioning SEARCH feature, this post was hard to find,

but I knew I had answered it just a while back.

Why did you repeat the question???
Did you even look at my solution??

www.jiskha.com/questions/1882225/using-the-completing-the-square-technique-the-maximum-value-of-the-function