Giải thích các bước giải:
$B = \dfrac{x}{\sqrt{x} - 1} - \dfrac{2x - \sqrt{x}}{x - \sqrt{x}}$ (với $x > 0, x \neq 1$)
$= \dfrac{x\sqrt{x}}{\sqrt{x}\left ( \sqrt{x} - 1 \right )} - \dfrac{2x - \sqrt{x}}{\sqrt{x}\left ( \sqrt{x} - 1 \right )}$
$= \dfrac{x\sqrt{x} - 2x + \sqrt{x}}{\sqrt{x}\left ( \sqrt{x} - 1 \right )}$
$= \dfrac{\sqrt{x}\left ( x - 2\sqrt{x} + 1 \right )}{\sqrt{x}\left ( \sqrt{x} - 1 \right )}$
$= \dfrac{\sqrt{x}\left ( \sqrt{x} - 1 \right )^{2}}{\sqrt{x}\left ( \sqrt{x} - 1 \right )}$
$= \sqrt{x} - 1$
