2: \(=6\sqrt{3}+3\sqrt{3}-\sqrt{3}=8\sqrt{3}\)
4:
\(=4+\sqrt{7}+4-\sqrt{7}-2\sqrt{16-7}=8-2\cdot3=2\)
6: \(=3\sqrt{2}-12\sqrt{2}+8\sqrt{2}-5\sqrt{2}=-6\sqrt{2}\)
8: \(=3\sqrt{2}-3\sqrt{2}+2\sqrt{2}+6\sqrt{2}=8\sqrt{2}\)
10: \(=3\sqrt{3}+5\sqrt{3}-20\sqrt{3}+2\sqrt{3}=-10\sqrt{3}\)
12: \(=9\sqrt{2}-10\sqrt{2}+4\sqrt{2}=3\sqrt{2}\)