\[3x^{2} - 4x - 7\]
\[D = ( - 4)^{2} - 4 \cdot 3 \cdot ( - 7) =\]
\[= 16 + 84 = 100\]
\[x_{1} = \frac{4 + \sqrt{100}}{3 \cdot 2} = \frac{4 + 10}{6} = \frac{14}{6} =\]
\[= \frac{7}{3}\]
\[x_{2} = \frac{4 - \sqrt{100}}{2 \cdot 3} = \frac{4 - 10}{6} = \frac{- 6}{6} =\]
\[= - 1\]
\[3x^{2} - 4x - 7 =\]
\[= 3 \bullet \left( x - \frac{7}{3} \right)(x + 1) =\]
\[= (3x - 7)(x + 1).\]