Your Nx is incorrect. It should be 3y^2 + 40xy^3. That might clear things up a bit for you.
ok so in this problem i have to solve for K to make the problem exact, that means My = Nx. so here is the problem.
(y^3 + kxy^4 - 2x)dx + (3xy^2 + 20x^2y^3)dy = 0
so My= 3y^2 + 4kxy^3 and Nx=3y^2+60x^2y^2
the answer in the book says 10, but i don't see how they got that from what i have k is not going to be a number.any help would be appreciated.
thanks in advance.