Please see attached jpeg for question and my attempt at a solution.
I understand that the method for extracting the constants Bn, Cm must be using orthogonality, and i've tried my best to use that. However, the sum which is a function of x which i have bracketed as * is causing me problems. I know for sure that the answer for Cm (or Cp) is what is within the square box, but I don't understand where the * sum goes... because it doesn't disappear when doing the integral does it?
PS apologies for the quality of the picture, all of the first line is in fact visible in case you are wondering, the only thing that you can't see is the close right bracket.
I just can't decide