If $f(x)=5^x$ and $g(x)=-2$, then $-f(g(x))$ = ?

$-25$

$-\sqrt{5}$

$-\dfrac{1}{25}$

$2$

$25$

Approach

$$ -f(g(x)) = -f(-2) $$ $$ = -(5^{-2}) $$ $$ = -\left(\frac{1}{5^2}\right) $$ $$ = \boxed{-\frac{1}{25}} $$