Giải thích các bước giải:
$A = \dfrac{a^{2} + \sqrt{a}}{a - \sqrt{a} + 1} - \dfrac{2a + \sqrt{a}}{\sqrt{a}} + 1$ (ĐK $a > 0$)
$= \dfrac{\sqrt{a}\left ( \sqrt{a^{3}} + 1 \right )}{a - \sqrt{a} + 1} - \dfrac{\sqrt{a}\left ( 2\sqrt{a} + 1 \right )}{\sqrt{a}} + 1$
$= \dfrac{\sqrt{a}\left ( \sqrt{a} + 1 \right )\left ( a - \sqrt{a} + 1 \right )}{a - \sqrt{a} + 1} - 2\sqrt{a} - 1 + 1$
$= \sqrt{a}\left ( \sqrt{a} + 1 \right ) - 2\sqrt{a} - 1 + 1$
$= a + \sqrt{a} - 2\sqrt{a} - 1 + 1$
$= a - \sqrt{a}$
