\[\begin{array}{l}
P = \frac{{2\sqrt a }}{{\sqrt a + 3}} + \frac{{\sqrt a + 1}}{{\sqrt a - 3}} + \frac{{3 + 7\sqrt a }}{{9 - a}}\\
P = \frac{{2\sqrt a }}{{\sqrt a + 3}} + \frac{{\sqrt a + 1}}{{\sqrt a - 3}} - \frac{{3 + 7\sqrt a }}{{\left( {\sqrt a - 3} \right)\left( {\sqrt a + 3} \right)}}\\
P = \frac{{2\sqrt a \left( {\sqrt a - 3} \right) + \left( {\sqrt a + 3} \right)\left( {\sqrt a + 1} \right) - \left( {3 + 7\sqrt a } \right)}}{{\left( {\sqrt a - 3} \right)\left( {\sqrt a + 3} \right)}}\\
P = \frac{{3a - 9\sqrt a }}{{\left( {\sqrt a - 3} \right)\left( {\sqrt a + 3} \right)}}\\
P = \frac{{3\sqrt a \left( {\sqrt a - 3} \right)}}{{\left( {\sqrt a - 3} \right)\left( {\sqrt a + 3} \right)}}\\
P = \frac{{3\sqrt a }}{{\sqrt a + 3}}
\end{array}\]
