分母の有理化

問題次の式の分母を有理化せよ。$${\small (1)}~\frac{\sqrt{6}-4}{\sqrt{2}}$$$${\small (2)}~\frac{\sqrt{2}}{2-\sqrt{3}}$$$${\small (3)}~\frac{1}{\sqrt{3}-1}-\frac{1}{\sqrt{3}+1}$$