Answer
$xy\sqrt{y}$
Work Step by Step
RECALL:
For any non-negative real number,
$\sqrt{a^2} = a$
Factor the radicand (which is the expression inside the radical sign) so that at least one factor is a square, and then simplify using the rule above to obtain:
$=\sqrt{(x^2y^2)(y)}
\\=\sqrt{(xy)^2(y)}
\\=xy\sqrt{y}$