Question

\sqrt{y}+3\sqrt{x}\left(2\sqrt{y}\right)-\sqrt{xy}

Answer 1

$\bf \sqrt{y}+3\sqrt{x}(2\sqrt{y})-\sqrt{xy}\implies \sqrt{y}+(3\cdot 2)\sqrt{x\cdot y}-\sqrt{xy} \\\\\\ \sqrt{y}+6\sqrt{xy}-\sqrt{xy}\implies \stackrel{\textit{adding like-terms}}{\sqrt{y}+5\sqrt{xy}}$