Question

If f(x)=cos3x and g(x)=(x+3)2, what is f'(g(x))?

Answer 1

$f(x) = cos3x \: \: \: \: \: g(x) = {(x + 3)}^{2} \\ \\ f(g(x)) = \cos(3 {(x + 3)}^{2} ) \\ \\ derivativef(g(x)) \\ \\ = - \sin(3 {x}^{2} + 27 + 18x) \times(6x + 18$