a , Ta có :
\(M=\left(\dfrac{\sqrt{x}+\sqrt{x}}{\sqrt{x}-1}\right):\left[\dfrac{2\left(\sqrt{x}+1\right)}{x\left(\sqrt{x}+1\right)}+\dfrac{x-2}{x\left(\sqrt{x}+1\right)}\right]\)
\(M=\dfrac{2\sqrt{x}}{\sqrt{x}-1}:\left[\dfrac{2\sqrt{x}+2+x-2}{x\left(\sqrt{x}+1\right)}\right]\)
\(M=\dfrac{2\sqrt{x}}{\sqrt{x}-1}.\dfrac{x\left(\sqrt{x}+1\right)}{2\sqrt{x}+x}\)
\(M=\dfrac{2x\sqrt{x}\left(\sqrt{x}+1\right)}{\left(2\sqrt{x}+x\right)\left(\sqrt{x}-1\right)}\)
\(M=\dfrac{2x\left(\sqrt{x}+1\right)}{\left(\sqrt{x}+2\right)\left(\sqrt{x}-1\right)}\)
b , thay vào rồi tính nhé .