Differentiate:

$y=\frac{x^4}{1-x^3}$

$\frac{x^3(x^4-3)}{(x^3-1{)}^2}$

$\frac{(x^3-1{)}^2}{x^3(x^4-3)}$

$\frac{x^3(x^3-4)}{(x^3-1{)}^2}$

$\frac{4x^3}{1-3x^2}$

$\frac{x^3(x^3-1)}{(x^3-4{)}^2}$