# How do you differentiate f(x) = cos (3x -3) using the chain rule?

$- 3 \sin \left(3 x - 3\right)$
$\frac{d}{\mathrm{dx}} \cos \left(3 x - 3\right) = - \sin \left(3 x - 3\right) \cdot \frac{d}{\mathrm{dx}} \left(3 x - 3\right)$
$= - 3 \sin \left(3 x - 3\right)$