Simplify $
\root 3 \of {x \root 3 \of {x \root 3 \of {x \sqrt{x}}}}.
$ Express your answer in simplest radical form in terms of $x$.
We have

\begin{align*}
\root 3 \of {x \root 3 \of {x \root 3 \of {x\sqrt{x}}}}
&= (x(x(x\cdot x^{\frac{1}{2}})^{\frac{1}{3}})^{\frac{1}{3}})^{\frac{1}{3}} \\
&= (x(x(x^{\frac{3}{2}})^{\frac{1}{3}})^{\frac{1}{3}})^{\frac{1}{3}} \\
&= (x(x \cdot x^{\frac{1}{2}})^{\frac{1}{3}})^{\frac{1}{3}}\\
&= (x(x^{\frac{3}{2}})^{\frac{1}{3}})^{\frac{1}{3}} = (x\cdot x^{\frac{1}{2}})^{\frac{1}{3}}
= (x^{\frac{3}{2}})^{\frac{1}{3}} = x^{\frac{1}{2}}=\boxed{\sqrt{x}}.
\end{align*}