Question

Find f ′(x) for f(x) = cos (3x^3).

Answer 1

$\bf f(x)=cos(3x^3)\impliedby chain-rule \\\\\\ \cfrac{df}{dx}=-sin(3x^3)\cdot (3\cdot 3x^{3-1})\implies \cfrac{df}{dx}=-9x^2sin(3x^3)$