a)

$2\sqrt{24}-3\sqrt{150}-9\sqrt{96}+2\sqrt{486}=2\sqrt{4\cdot 6}-3\sqrt{25\cdot 6}-9\sqrt{16\cdot 6}+2\sqrt{81\cdot 6}=$

$=2\sqrt{4}\sqrt{6}-3\sqrt{25}\sqrt{6}-9\sqrt{16}\sqrt{6}+2\sqrt{81}\sqrt{6}=2\cdot 2\sqrt{6}-3\cdot 5\sqrt{6}-9\cdot 4\sqrt{6}+2\cdot 9\sqrt{6}=$