Incorrect. Use the facts that $\displaystyle{243}={{3}}^{{5}}\usepackage{cmbright}\Huge\$ and $\displaystyle{{243}}^{{\frac{{2}}{{5}}}}={{\left({{243}}^{{\frac{{1}}{{5}}}}\right)}}^{{2}}\usepackage{cmbright}\Huge\$ to help you solve this problem.