1. The problem statement, all variables and given/known data The differential equation: (1-y2) dx + (1-x2) dy = 0 the integrating factor is of the form μ(x,y) = f(xy). Find f 2. The attempt at a solution I have tried many times to get a function of (xy) such that the LHS of the differential equation to be exact. I have tried the integrating factor 1/[(1-y^2)(1-x^2)] and it works..... but it is definitely not a function of the term (xy)... Any hints on how should I find it? Or is there any formal way to find it?