#### Answer

$F(x)=f\circ g(x)$ for
$g(x)=2x+x^{2},\qquad f(x)=x^{4}$

#### Work Step by Step

$f\circ g(x)=f[g(x)]$
Rule of thumb: Ask yourself
what would be the last operation if you used a calculator, step by step?
(Answer: Raise to the 4th power)
$f(x)=x^{4}$
$F(x)=f(2x+x^{2})$
So, if
$g(x)=2x+x^{2}$ and $f(x)=x^{4}$
then
$F(x)=f\circ g(x)$
$g(x)=2x+x^{2},\qquad f(x)=x^{4}$