General solution to a 2nd order differential :( 1. The problem statement, all variables and given/known data What is the general solution of ∂2f(x,t)/∂x∂t = xt ? 2. Relevant equations 3. The attempt at a solution I have no idea, I tried to follow an example out of the book but it was quite different to this question. Do I need to replace x's and y's with u's and v's? If so, how?