Let so your ODE becomes . See how that goes.
When I see a problem like this, and I want to find out what integrating factor there might be, I, with the help of Danny there, have worked out a decently general method. It won't solve every first-order, but it will do many. It works like this: assume an integrating factor of the form
where h is an unknown function. The idea is that you hope to be able to obtain a differential equation that governs the behavior of h. You multiply the DE by this integrating factor thus:
You then utilize the conditions for exactness:
So you take your derivatives and boil it all down. The hope is to get a separable DE for h. I get the following:
You have some freedoms here with m and n. I can see that if I choose m = 0, the equation simplifies drastically. You should be able to finish from here.
So here's a decently general method for solving quite a few integrating factor-type nonlinear problems.