1. The problem statement, all variables and given/known data xy''+2y'+(n^2)*x*y=sin(omega*x) Hint: Eliminate the first derivative term 2. Relevant equations 3. The attempt at a solution I have tried lots of substitutions, but none of them seems to work out. I don't really understand what the hint is getting at. For example, I've tried y'=ux, but then I don't know what to do with the y. I've tried y=ux, but that doesn't seem to help matters at all. And I've tried numerous other silly things that haven't worked out. I'm really out of ideas and stuck. Any little hints would be greatly appreciated.