1. The problem statement, all variables and given/known data Find the function M such that M(x, y)dx+(x^2-y^2)dy=0 is exact. 2. Relevant equations This is an exact equation. 3. The attempt at a solution Here's my work: integral of (x^2-y^2)dy=yx^2-y^3/3+h(x)=C 2xy+h'(x)=M(x, y) But the answer in the book is M(x, y)=2xy+f(x). How do I get to the answer from there?