Question

Let f be a function defined by f(x) = x^2 for -1 < x < 1 where f(x + 2) = f(x). Then,
1) Find the Fourier series representation of f(x).
2) Use the above result to show that pi^2/12 = ∑ n=1 to ∞ (-1)^n+1 × 1/n^n.