Rút gọn các biểu thức sau
D = \(\left(\frac{5}{x-\sqrt{x}-6}+\frac{1}{\sqrt{x}+2}\right):\frac{1}{\sqrt{x}-3}\)
E =\(\left(\frac{1}{a-\sqrt{a}}+\frac{1}{\sqrt{a-1}}\right):\frac{\sqrt{a+1}}{a-2\sqrt{a}+1}\)
F = \(\left(\frac{1}{\sqrt{a-1}}+\frac{1}{a-\sqrt{a}}\right):\left(\frac{1}{\sqrt{a}+1}+\frac{2}{a-1}\right)\)