This is what I see - I don't know if it'll help
Working with Tenenbaum's ODE page 91, problem 17, , can't figure it out. Here are some pieces of information that could be useful, given the methods of finding an integrating factor discussed in the chapter:
Now I need to take or it times or , and divide it by (a) or (b) so that the result is a function of , or . But none of it seems to work. The book says that the integrating factor necessary is , but I don't see how you could possibly obtain that with the methods discussed in the chapter.