$\displaystyle (9x^2 + y -1)dx - (4y -x)dy = 0, y(0) = 1$

solve the given initial value problem and determine at least approximately where the solution is valid.

Can someone help me with this? im not quite sure how to really start this problem, I got that after integrating

$\displaystyle 3x^3 -x = 2y^2$

but im not sure where to go. The equations came out as exact after partial differentiating both with respect to each other x and y.