Đáp án:
$A = \sqrt x-1$
Giải thích các bước giải:
$\begin{array}{l}\quad A = \dfrac{x}{\sqrt x-1} - \dfrac{2x-\sqrt x}{x-\sqrt x}\qquad (x >0;\, x \ne 1)\\ \to A = \dfrac{x}{\sqrt x-1} - \dfrac{\sqrt x(2\sqrt x-1)}{\sqrt x(\sqrt x-1)}\\ \to A = \dfrac{x}{\sqrt x-1} - \dfrac{2\sqrt x-1}{\sqrt x-1}\\ \to A = \dfrac{x - 2\sqrt x + 1}{\sqrt x-1}\\ \to A = \dfrac{(\sqrt x-1)^2}{\sqrt x -1}\\ \to A = \sqrt x-1 \end{array}$
