Answer
$11\sqrt7$
Work Step by Step
Simplify each radical to obtain:
\begin{align*}
&=3\sqrt{9(7)}+\sqrt{4(7)}\\
&=3\sqrt{3^2(7)}+\sqrt{2^2(7)}\\
&=3(3)\sqrt7+(2\sqrt7)\\
&=9\sqrt7+2\sqrt7
\end{align*}
Recall:
For any real numbers $a, b, $ and $c$,
$$a(b+c)=ab+ac$$
Use the rule above to obtain:
\begin{align*}
9\sqrt{7}+2\sqrt{7}&=(9+2)\sqrt{7}\\
&=11\sqrt{7}\\
\end{align*}