\[6a^{2} + 5a + 1 = 0\]
\[D = 25 - 24 = 1\]
\[a_{1} = \frac{- 5 + 1}{12} = - \frac{4}{12} = - \frac{1}{3};\ \ \ \]
\[a_{2} = \frac{- 5 - 1}{12} = - \frac{6}{12} = - 0,5\]
\[Ответ:a = - \frac{1}{3};\ \ \ a = - 0,5.\]