Упростите выражение: 2/(a-3)-a/(a-3)^2-a/(a^2-9).

\[\frac{2}{a - 3} - \frac{a}{(a - 3)^{2}} - \frac{a}{a^{2} - 9} = \frac{2^{{\backslash a}^{2} - 9}}{a - 3} -\]

\[- \ \frac{a^{\backslash a + 3}}{(a - 3)^{2}} - \frac{a^{\backslash a - 3}}{(a - 3)(a + 3)} =\]

\[= \frac{2a^{2} - 18 - a^{2} - 3a - a^{2} + 3a}{(a - 3)^{2}(a + 3)} =\]

\[= - \frac{18}{(a - 3)^{2}(a + 3)} =\]