Answer
$x^2\sqrt{x}$
Work Step by Step
Factor the radicand (expression inside the radical sign) so that at least one factor is a square to obtain:
$=\sqrt{x^4(x)}
\\=\sqrt{(x^2)^2(x)}$
The principal square root is always non-negative.
However, the value of $x^2$ will never be negative.
Thus,
$\sqrt{(x^2)^2(x)}=x^2\sqrt{x}$