Answer
$$\frac{x^2}{2}$$
Work Step by Step
RECALL:
(1) If $n$ is odd, then $\sqrt[n]{a^n}=a$.
(2) If $n$ is even, then $\sqrt[n]{a^n} = |a|$
Use rule (1) above to obtain:
\begin{align*}
\sqrt{\frac{9x^4}{36}}&=\sqrt{\frac{9}{36} \cdot x^4}\\\\
&=\sqrt{\left(\frac{3}{6}\right)(x^2)^2}\\\\
&=\frac{3}{6}\cdot |x^2|\\\\
&=\frac{1}{2}\cdot |x^2|
\end{align*}
However, since $|x^2|$ will never be negative, then $|x^2|=x^2$.
Thus, the solution is:
$$=\frac{1}{2}x^2\\\\
=\frac{x^2}{2}$$
