ĐKXĐ: ...
\(A=\left(\frac{x+\sqrt{x}-x-2}{\sqrt{x}+1}\right):\left(\frac{\sqrt{x}\left(\sqrt{x}-1\right)+\sqrt{x}-4}{\left(\sqrt{x}+1\right)\left(\sqrt{x}-1\right)}\right)\)
\(=\left(\frac{\sqrt{x}-2}{\sqrt{x}+1}\right):\left(\frac{x-4}{\left(\sqrt{x}-1\right)\left(\sqrt{x}+1\right)}\right)=\frac{\left(\sqrt{x}-2\right)\left(\sqrt{x}-1\right)\left(\sqrt{x}+1\right)}{\left(\sqrt{x}+1\right)\left(\sqrt{x}-2\right)\left(\sqrt{x}+2\right)}\)
\(=\frac{\sqrt{x}-1}{\sqrt{x}+2}\)