I'm trying to differentiate this function: $\displaystyle f(x)=x^4(1-4x^2)^3$

$\displaystyle =x^4(3)(1-4x^2)^2(-8x)+4x^3(1-4x^2)^3$

is that correct so far? The book has the answer as $\displaystyle -4 x^3 (1-4 x^2)^2 (10 x^2-1)$, so I'm wondering if I was doing anything wrong.