\(\sqrt{18}(\sqrt{6}-\sqrt{2})-3\sqrt{12} = \sqrt{18} \cdot \sqrt{6} - \sqrt{18} \cdot \sqrt{2} - 3\sqrt{12}
\(\sqrt{18} = \sqrt{9 \cdot 2} = 3\sqrt{2}
\(\sqrt{12} = \sqrt{4 \cdot 3} = 2\sqrt{3}
3\sqrt{2} \cdot \sqrt{6} - 3\sqrt{2} \cdot \sqrt{2} - 3 \cdot (2\sqrt{3})
3\sqrt{12} - 3 \cdot 2 - 6\sqrt{3}
3 \cdot (2\sqrt{3}) - 6 - 6\sqrt{3}
6\sqrt{3} - 6 - 6\sqrt{3}
-6
Ответ: -6