It happens that I'm not good with integrals, and our teacher is a good teacher, but has a little problem: he uses easy examples but gives us difficult homework... I've managed to do most of it, but have trouble with last ones... can anyone help me please? I'm desperate !!!

I-Solve the next lineal equations:

4.-

II- Find the general solution for the next exact ordinary equations:

(I know the first one of these is not exact... but can it be solved with an integrating factor?... and the last one... I know it says general solution too... do you think is a trap from my teacher [last time he said "one of the problems didn't have any solution", so I get that wrong...])

Also... procedures will be highly appreciated n__n"

And, after the answers... can someone teach me the art of EDO?... I'll be very grateful, thanks in advance.