# How do you simplify (3z^2)^2 and write it using only positive exponents?

$a = {a}^{\textcolor{red}{1}}$ and ${\left({x}^{\textcolor{red}{a}}\right)}^{\textcolor{b l u e}{b}} = {x}^{\textcolor{red}{a} \times \textcolor{b l u e}{b}}$
${\left(3 {z}^{2}\right)}^{2} = {\left({3}^{\textcolor{red}{1}} {z}^{\textcolor{red}{2}}\right)}^{\textcolor{b l u e}{2}} = {3}^{\textcolor{red}{1} \times \textcolor{b l u e}{2}} {z}^{\textcolor{red}{2} \times \textcolor{b l u e}{2}} = {3}^{2} {z}^{4} = 9 {z}^{4}$