Answer
$\sqrt [4] {x^2y}$
Work Step by Step
Simplify. $\sqrt {\sqrt {x^2y}}$
Since, $\sqrt[n] {p^m}=p^{\frac{m}{n}}$
Thus,
$\sqrt {\sqrt {x^2y}}=\sqrt {(x^2y)^{\frac{1}{2}}}=((x^2y)^{\frac{1}{2}})^{\frac{1}{2}}$
or, $=(x^2y)^{\frac{1}{4}}$
ore, $=\sqrt [4] {x^2y}$
