# Question #806c4

The answer is ${t}^{3} - 4 {t}^{2} + 4$
$f \left(t\right) = t + 4$
$g \left(t\right) = {t}^{3} - 4 {t}^{2}$
So $f \left(g \left(t\right)\right) = f \left({t}^{3} - 4 {t}^{2}\right) = {t}^{3} - 4 {t}^{2} + 4$
and $g \left(f \left(t\right)\right) = g \left(t + 4\right) = {\left(t + 4\right)}^{3} - 4 {\left(t + 4\right)}^{2}$
In all cases $f \left(g \left(t\right)\right) \ne g \left(f \left(t\right)\right)$