Answer
$y' = \frac{12x^2 + 1}{4y^3 - 2}$
Work Step by Step
$\frac{d}{dx}(y^4)-\frac{d}{dx}(2y) = \frac{d}{dx}(4x^3) + \frac{d}{dx}(x)$
$4y^3y' - 2y' = 4*3x^2 + 1$
Now we have to solve for $y'$:
$y'(4y^3 - 2) =12x^2 + 1$
$y' = \frac{12x^2 + 1}{4y^3 - 2}$