[tex]\bf \sqrt{2}\left(3\sqrt{2}+\sqrt{18} \right)~~
\begin{cases}
18=2\cdot 3\cdot 3\\
\qquad 2\cdot 3^2
\end{cases}\implies \sqrt{2}\left(3\sqrt{2}+\sqrt{2\cdot 3^2} \right)
\\\\\\
\sqrt{2}\left(3\sqrt{2}+3\sqrt{2} \right)\implies \sqrt{2}\left(6\sqrt{2} \right)\implies 6\left(\sqrt{2}\right)^2\implies 6\cdot 2\implies \stackrel{rational}{12}[/tex]
