\(A=\dfrac{1+\sqrt{a}-1+\sqrt{a}}{1-a}\cdot\dfrac{1+\sqrt{a}}{\sqrt{a}}=\dfrac{2}{1-\sqrt{a}}\)
\(B=\dfrac{1+2\sqrt{b}+b-\left(1-2\sqrt{b}+b\right)+4b}{1-b}\)
\(=\dfrac{4b+4\sqrt{b}}{-\left(\sqrt{b}+1\right)\left(\sqrt{b}-1\right)}=-\dfrac{4\sqrt{b}}{\sqrt{b}-1}\)
\(C=\dfrac{2\sqrt{a}}{\sqrt{a}+3}+\dfrac{\sqrt{a}}{\sqrt{a}-3}-\dfrac{3a+3}{a-9}\)
\(=\dfrac{2a-6\sqrt{a}+a+3\sqrt{a}-3a-3}{a-9}=\dfrac{-3\sqrt{a}-3}{a-9}\)
\(E=\dfrac{x-5\sqrt{x}+4-9\sqrt{x}+4}{x-16}-\dfrac{4\sqrt{x}-4}{\sqrt{x}-4}\)
\(=\dfrac{x-4\sqrt{x}-\left(4\sqrt{x}-4\right)\left(\sqrt{x}+4\right)}{x-16}\)
\(=\dfrac{x-4\sqrt{x}-4x-16\sqrt{x}+4\sqrt{x}+16}{\left(\sqrt{x}-4\right)\left(\sqrt{x}+4\right)}\)
\(=\dfrac{-3x-16\sqrt{x}+16}{x-16}\)
