\[3x^{2} + 14x - 5\]
\[D_{1} = 49 + 15 = 64\]
\[x_{1} = \frac{- 7 + 8}{3} = \frac{1}{3};\ \]
\[x_{2} = \frac{- 7 - 8}{3} = - 5.\]
\[3x^{2} + 14x - 5 = 3 \cdot \left( x - \frac{1}{3} \right)(x + 5) =\]
\[= (3x - 1)(x + 5).\]