Đáp án:
\(\dfrac{{x\sqrt x - 4x + 13\sqrt x }}{{\left( {\sqrt x + 3} \right)\left( {\sqrt x - 3} \right)}}\)
Giải thích các bước giải:
\(\begin{array}{l}
DK:x \ge 0;x \ne 9\\
A = \dfrac{{\sqrt x \left( {\sqrt x - 3} \right)}}{{\sqrt x + 3}} + \dfrac{{2\sqrt x - 1}}{{\sqrt x - 3}} - \dfrac{{2\sqrt x - \sqrt x - 3}}{{x - 9}}\\
= \dfrac{{\sqrt x \left( {x - 6\sqrt x + 9} \right) + \left( {2\sqrt x - 1} \right)\left( {\sqrt x + 3} \right) - 2\sqrt x + \sqrt x + 3}}{{\left( {\sqrt x + 3} \right)\left( {\sqrt x - 3} \right)}}\\
= \dfrac{{x\sqrt x - 6x + 9\sqrt x + 2x + 6\sqrt x - \sqrt x - 3 - 2\sqrt x + \sqrt x + 3}}{{\left( {\sqrt x + 3} \right)\left( {\sqrt x - 3} \right)}}\\
= \dfrac{{x\sqrt x - 4x + 13\sqrt x }}{{\left( {\sqrt x + 3} \right)\left( {\sqrt x - 3} \right)}}
\end{array}\)
