\[3x^{2} - 10x - 8\]
\[D_{1} = 25 + 24 = 49\]
\[x_{1} = \frac{5 + 7}{3} = 4;\ \ \]
\[x_{2} = \frac{5 - 7}{3} = - \frac{2}{3}.\]
\[3x^{2} - 10x - 8 = 3 \cdot \left( x + \frac{2}{3} \right)(x - 4) =\]
\[= (3x + 2)(x - 4).\]