1) Ta có: \(A=\dfrac{2x^2+2}{1-x^2}-\dfrac{1}{1+\sqrt{x}}-\dfrac{1}{1-\sqrt{x}}\)
\(=\dfrac{-2x^2-2}{\left(\sqrt{x}-1\right)\left(\sqrt{x}+1\right)\left(x+1\right)}-\dfrac{1}{\sqrt{x}+1}+\dfrac{1}{\sqrt{x}-1}\)
\(=\dfrac{-2x^2-2-\left(\sqrt{x}-1\right)\left(x+1\right)+\left(x+1\right)\left(\sqrt{x}+1\right)}{\left(x+1\right)\left(\sqrt{x}-1\right)\left(\sqrt{x}+1\right)}\)
\(=\dfrac{-2x^2-2-x\sqrt{x}-\sqrt{x}+x+1+x\sqrt{x}+x+\sqrt{x}+1}{\left(x+1\right)\left(\sqrt{x}-1\right)\left(\sqrt{x}+1\right)}\)
\(=\dfrac{-2x^2+2x}{\left(x+1\right)\left(\sqrt{x}-1\right)\left(\sqrt{x}+1\right)}\)
\(=\dfrac{-2x\left(x-1\right)}{\left(x+1\right)\left(x-1\right)}\)
\(=\dfrac{-2x}{x+1}\)