# How do you find the derivative of R(w)=w^3*cos(4w)?

##### 1 Answer
Apr 20, 2017

$R ' \left(w\right) = {w}^{2} \left(3 \cos 4 w - 4 w \sin 4 w\right)$

#### Explanation:

$R ' \left(w\right) = \left({w}^{3}\right) ' \cos 4 w + {w}^{3} \left(\cos 4 w\right) '$

$R ' \left(w\right) = 3 {w}^{2} \cos 4 w - 4 {w}^{3} \sin 4 w$

$R ' \left(w\right) = {w}^{2} \left(3 \cos 4 w - 4 w \sin 4 w\right)$