1. The problem statement, all variables and given/known data (3y4-11x2y2-28x4)dx-(4xy3)dy=0 2. Relevant equations My=Nx if equation is exact, if not, I can make it exact (I hope) by finding an integrating factor. The problem is I can't get the integrating factor to be a function of x or y only. 3. The attempt at a solution Let stuff in front of dx=M Let stuff in front of dy=N My=12y3-22x2y Nx=-4y3 My-Nx=16y3-22x2y First try (My-Nx)/N=(16y3-22x2y)/4xy3 Not a function of x only. Then (My-Nx)/-M=16y3-22x2y/-(3y4-11x2y2) Not a function of y only. Am I using the wrong method to solve this question? I don't see any other way to go about it rather than turning this into an exact equation. Why can't I find an integrating factor that has a pure x or y expression? Thanks.