1. The problem statement, all variables and given/known data Compute the fourier sine series for the given function: f(x) = -1 0<x<1 2. Relevant equations http://mathworld.wolfram.com/FourierSineSeries.html 3. The attempt at a solution I got: bn = 2 * integral( (-1) * sin(npix) dx) from 0 to 1 = 2*(-1)^n/(npi) however, the answer in the back of the book turns n=2k-1 I don't get why it does this! For most of the problems I've done so far, n has always just been n, why did they suddenly replace it with 2k-1? How do I know when I should set n equal to something and when not to? How do I know what n should be equal to?