1. The problem statement, all variables and given/known data The question is as attached in the picture. 3. The attempt at a solution I haven't got to the answer, but I wonder if this is OK: g(y) = ∫ f(x,y) dx = F(y) - F(0,y) (dg/dy) = f(y) - f(0,y) Since the 'x' is just a dummy variable where the final function g will be in terms of y. By integrating it with respect to x, then filling it in with 0 and y, by differentiating g does it reverse back the integration process and simply filling it with 0 and y?