DE

( 2x³ - y⁴) dx + xy³ dy= 0

We can solve that the integrating factor is $x^{-5}$ which gives the general solution

$-\dfrac{2}{x} + \dfrac{y^4}{4x^4} = C$

which simplifies to $\boxed{y^4 = 8x^3 + Cx^4}$