\[\frac{x^{2} - 4}{3} + 4x = 3\ \ \ \ | \cdot 3\]
\[x^{2} - 4 + 12x = 9\]
\[x² + 12x - 13 = 0\ \]
\[D = b^{2} - 4ac =\]
\[= 144 - 4 \cdot 1 \cdot ( - 13) =\]
\[= 144 + 52 = 196\]
\[x_{1} = \frac{- 12 + 14}{2} = \frac{2}{2} = 1\]
\[x_{2} = \frac{- 12 - 14}{2} = - \frac{26}{2} = - 13\]
\[Ответ:x_{1} = 1;\ \ x_{2} = - 13.\]