算式 \frac{6}{\sqrt{7}-\sqrt{5}}-\frac{12}{\sqrt{11}+\sqrt{5}} 之值為何？
\frac{6}{\sqrt{7}-\sqrt{5}}-\frac{12}{\sqrt{11}+\sqrt{5}}
3\sqrt2-3
6\sqrt3-2\sqrt6
3\sqrt7-5\sqrt5-2\sqrt{11}
3\sqrt7+5\sqrt5-2\sqrt{11}
