f (x) = 0 -pi<x<0
Find the fourier series and use it to show that
The Attempt at a Solution
I was able to find the fourier series and my answer matched with the back of the book. But I don't understand how I am supposed to use it to prove the expansion of pi^2/6 . I tried plugging in (pi^2)/6 for f(x) but that didn't work out.