Đáp án:
$\begin{array}{l}
Dkxd:\left\{ \begin{array}{l}
x \ge 0\\
x \ne \dfrac{1}{9}
\end{array} \right.\\
P = \left( {\dfrac{{\sqrt x - 1}}{{3\sqrt x - 1}} - \dfrac{1}{{3\sqrt x + 1}} + \dfrac{{8\sqrt x }}{{9x - 1}}} \right)\\
:\left( {1 - \dfrac{{3\sqrt x - 2}}{{3\sqrt x + 1}}} \right)\\
= \dfrac{{\left( {\sqrt x - 1} \right)\left( {3\sqrt x + 1} \right) - 3\sqrt x + 1 + 8\sqrt x }}{{\left( {3\sqrt x - 1} \right)\left( {3\sqrt x + 1} \right)}}:\\
\dfrac{{3\sqrt x + 1 - 3\sqrt x + 2}}{{3\sqrt x + 1}}\\
= \dfrac{{3x - 2\sqrt x - 1 + 5\sqrt x + 1}}{{\left( {3\sqrt x - 1} \right)\left( {3\sqrt x + 1} \right)}}.\dfrac{{3\sqrt x + 1}}{3}\\
= \dfrac{{3x + 3\sqrt x }}{{3\sqrt x - 1}}.\dfrac{1}{3}\\
= \dfrac{{x + \sqrt x }}{{3\sqrt x - 1}}
\end{array}$
