#### Answer

$a)$ $x^{2}\sqrt{x}$
$b)$ $x\sqrt[4]{x^{2}}$

#### Work Step by Step

$a)$ $\sqrt{x^{5}}$
Rewrite $x^{5}$ as $x^{4}\cdot x$ and evaluate:
$\sqrt{x^{5}}=\sqrt{x^{4}\cdot x}=x^{2}\sqrt{x}$
$b)$ $\sqrt[4]{x^{6}}$
Rewrite $x^{6}$ as $x^{4}\cdot x^{2}$ and evaluate:
$\sqrt[4]{x^{6}}=\sqrt[4]{x^{4}\cdot x^{2}}=x\sqrt[4]{x^{2}}$