Use the "mixed partials" check to see if the following differential equation is exact.

If it is exact find a function $F(x,y)$ whose differential, $dF(x,y)$ gives the differential equation. That is, level curves $F(x,y) = C$ are solutions to the differential equation: $$\frac{dy}{dx} = \frac{ 3 x^{2}- y }{ x+ 4 y^{3} }$$ First rewrite as $$M(x,y) \, dx + N(x,y) \, dy = 0$$ where $M(x,y)=$ ,
and $N(x,y)=$ .

If the equation is not exact, enter not exact, otherwise enter in $F(x,y)$ as the solution of the differential equation here $= C$.