[SOLVED] Seperation of variables - first order PDE 1. The problem statement, all variables and given/known data I have the expression X'(x)/X(x) = cx. How do I seperate the variables? It's the fraction on the left side that annoys me. I know that X'(x) = d(X(x))/dx, but I can't use this here? EDIT: Sorry for the mis-spelled title. It's "separation".