1. The problem statement, all variables and given/known data I have calculate my double integral using wolfram alpha , but i get the ans = 312.5 , but according to the book , the ans is = 0 , which part of my working is wrong 2. Relevant equations 3. The attempt at a solution Or is it z =0 , ? i have tried z = 0 , but still didnt get the ans = 0 , Which part is wrong?