I'm having trouble figuring out which method I should be using on some of these problems. Any help in figuring out which methods would be best is much appreciated.

1. (x^3 + y^3)dx - (3xy^2)dy = 0

2. xdy - ydx = sqrt(x^2 - y^2)dx

Just these two for now. Thanks in advance.

Edit: I tried the first one with Homogeneous method but I get to a point after substitution I can't integrate.