\[ax^{2} + 6x + 3a - 6 < 0\]
\[D = 36 - 4a(3a - 6) =\]
\[= 36 - 12a^{2} + 24a\]
\[Неравенство\ всегда\ верно\ \]
\[при\ D < 0:\]
\[36 - 12a^{2} + 24a < 0\ \ \ \ |\ :( - 12)\]
\[a^{2} - 2a - 3 > 0\]
\[a_{1} + a_{2} = 2;\ \ \ \ \ a_{1} \cdot a_{2} = - 3\]
\[a_{1} = - 1;\ \ \ \ a_{2} = 3.\]
\[(a + 1)(a - 3) > 0\]
\[a < - 1;\ \ \ \ a > 3.\]
\[Ветви\ параболы\ \]
\[направлены\ вниз:\]
\[a < 0.\]
\[Ответ:( - \infty; - 1).\]