Question

Can somebody help with these three questions plz

Answer 1

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