11.
\(=\frac{\sqrt{x}-3}{2-\sqrt{x}}+\frac{\sqrt{x}-2}{3+\sqrt{x}}+\frac{9-x}{(2-\sqrt{x})(\sqrt{x}+3)}\)
\(=\frac{(\sqrt{x}-3)(\sqrt{x}+3)}{(2-\sqrt{x})(\sqrt{x}+3)}+\frac{\sqrt{x}-2}{3+\sqrt{x}}+\frac{9-x}{(2-\sqrt{x})(\sqrt{x}+3)}\)
\(=\frac{x-9}{(2-\sqrt{x})(\sqrt{x}+3)}+\frac{\sqrt{x}-2}{3+\sqrt{x}}+\frac{9-x}{(2-\sqrt{x})(\sqrt{x}+3)}\)
\(=\frac{\sqrt{x}-2}{3+\sqrt{x}}\)
12.
\(=\frac{(3-\sqrt{x})(3\sqrt{x}-2)+(5\sqrt{x}+7)(3\sqrt{x}+4)}{(5\sqrt{x}+7)(3\sqrt{x}-2)}-\frac{42\sqrt{x}+34}{(5\sqrt{x}+7)(3\sqrt{x}-2)}\)
\(=\frac{12x+52\sqrt{x}+22}{(5\sqrt{x}+7)(3\sqrt{x}-2)}-\frac{42\sqrt{x}+34}{(5\sqrt{x}+7)(3\sqrt{x}-2)}\)
\(=\frac{12x+10\sqrt{x}-12}{(5\sqrt{x}+7)(3\sqrt{x}-2)}=\frac{2(3\sqrt{x}-2)(2\sqrt{x}+3)}{(5\sqrt{x}+7)(3\sqrt{x}-2)}=\frac{2(2\sqrt{x}+3)}{5\sqrt{x}+7}\)
13.
\(=\frac{(\sqrt{x}+2)(2\sqrt{x}-3)+(3\sqrt{x}-4)(-\sqrt{x}+2)}{(-\sqrt{x}+2)(2\sqrt{x}-3)}+\frac{-7\sqrt{x}+10}{(-\sqrt{x}+2)(2\sqrt{x}-3)}\)
\(=\frac{-x+11\sqrt{x}-14}{(-\sqrt{x}+2)(2\sqrt{x}-3)}+\frac{-7\sqrt{x}+10}{(-\sqrt{x}+2)(2\sqrt{x}-3)}\)
\(=\frac{-x+4\sqrt{x}-4}{(-\sqrt{x}+2)(2\sqrt{x}-3)}=\frac{-(\sqrt{x}-2)^2}{-(\sqrt{x}-2)(2\sqrt{x}-3)}=\frac{\sqrt{x}-2}{2\sqrt{x}-3}\)