ĐKXĐ: \(x>0;x\ne1\)
\(A=\left(\frac{1}{\sqrt{x}}-\frac{1}{2\sqrt{x}}\right):\left(\frac{\sqrt{x}\left(\sqrt{x}-1\right)^2-\sqrt{x}\left(\sqrt{x}+1\right)^2}{\left(\sqrt{x}+1\right)\left(\sqrt{x}-1\right)}\right)\)
\(=\frac{1}{2\sqrt{x}}:\left(\frac{\sqrt{x}\left[\left(\sqrt{x}-1\right)^2-\left(\sqrt{x}+1\right)^2\right]}{\left(\sqrt{x}+1\right)\left(\sqrt{x}-1\right)}\right)=\frac{1}{2\sqrt{x}}:\left(\frac{\sqrt{x}.4\sqrt{x}}{\left(\sqrt{x}-1\right)\left(\sqrt{x}+1\right)}\right)\)
\(=\frac{x-1}{8x\sqrt{x}}\)