Đáp án:
\(\dfrac{{3\sqrt x }}{{\sqrt x - 3}}\)
Giải thích các bước giải:
\(\begin{array}{l}
B = \dfrac{{2\sqrt x }}{{\sqrt x + 3}} + \dfrac{{\sqrt x + 1}}{{\sqrt x - 3}} + \dfrac{{3 - 11\sqrt x }}{{9 - x}}\\
= \dfrac{{2\sqrt x \left( {\sqrt x - 3} \right) + \left( {\sqrt x + 1} \right)\left( {\sqrt x + 3} \right) - 3 + 11\sqrt x }}{{\left( {\sqrt x - 3} \right)\left( {\sqrt x + 3} \right)}}\\
= \dfrac{{2x - 6\sqrt x + x + 4\sqrt x + 3 - 3 + 11\sqrt x }}{{\left( {\sqrt x - 3} \right)\left( {\sqrt x + 3} \right)}}\\
= \dfrac{{3x + 9\sqrt x }}{{\left( {\sqrt x - 3} \right)\left( {\sqrt x + 3} \right)}} = \dfrac{{3\sqrt x }}{{\sqrt x - 3}}
\end{array}\)
