$B=$$\frac{\sqrt{x}}{\sqrt{x}-1}-$ $\frac{2\sqrt{x}}{x-1}$ ĐK: x≥0 ; x≠1
$=\frac{\sqrt{x}(\sqrt{x}+1)}{(\sqrt{x}-1)(\sqrt{x}+1)}-$ $\frac{2\sqrt{x}}{(\sqrt{x}-1)(\sqrt{x}+1)}$
$=\frac{x+\sqrt{x}-2\sqrt{x}}{(\sqrt{x}-1)(\sqrt{x}+1)}$
$=\frac{x-\sqrt{x}}{(\sqrt{x}-1)(\sqrt{x}+1)}$
$=\frac{\sqrt{x}(\sqrt{x}-1)}{(\sqrt{x}-1)(\sqrt{x}+1)}$
$=\frac{\sqrt{x}}{\sqrt{x}+1}$
