# If f(x) =-e^(x)  and g(x) = tan^2x^2 , what is f'(g(x)) ?

First, take the derivative of $f \left(x\right)$.
$f ' \left(x\right) = - {e}^{x}$
Note that the derivative of ${e}^{x}$ is just ${e}^{x}$ and adding a negative to it won't change that.
Now, put in $g \left(x\right)$ for where there's a $x$ in $f \left(x\right)$
$f ' \left(g \left(x\right)\right) = - {e}^{{\tan}^{2} \left({x}^{2}\right)}$