Đáp án:
$\begin{array}{l}
P = \left( {\frac{1}{{a - \sqrt a }} + \frac{1}{{\sqrt a - 1}}} \right):\frac{{\sqrt a + 1}}{{a - 2\sqrt a + 1}}\left( {a > 0;a \ne 1} \right)\\
= \left( {\frac{1}{{\sqrt a \left( {\sqrt a - 1} \right)}} + \frac{1}{{\sqrt a - 1}}} \right):\frac{{\sqrt a + 1}}{{{{\left( {\sqrt a - 1} \right)}^2}}}\\
= \frac{{1 + \sqrt a }}{{\sqrt a \left( {\sqrt a - 1} \right)}}.\frac{{{{\left( {\sqrt a - 1} \right)}^2}}}{{\sqrt a + 1}}\\
= \frac{{\sqrt a - 1}}{{\sqrt a }}
\end{array}$
