\[6a - 12 = 0\]
\[a = 2,\ \ 5 \neq 0 \Longrightarrow нет\ корней\]
\[= 36a^{2} - 264a + 384 < 0\]
\[36a² - 264a + 384 < 0\ \ \ |\ :12\]
\[3a^{2} - 22a + 32 = 0\]
\[D = 484 - 384 = 100\]
\[a_{1} = \frac{22 + 10}{6} = 5\frac{1}{3}\]
\[a_{2} = \frac{22 - 10}{6} = 2\]
\[Ответ:\left\lbrack 2;5\frac{1}{3} \right).\]