Intermediate Algebra for College Students (7th Edition)

$\sqrt[9]{(xy)^4}$
RECALL: $a^{\frac{m}{n}}=\sqrt[n]{a^m}$ The given expression has $a=xy$, $m=4$ and $n=9$ Use the rule above to obtain: $(xy)^{\frac{4}{9}}=\sqrt[9]{(xy)^4}$