\[3x^{2} + 7x + 4\]
\[D = 7^{2} - 4 \cdot 3 \cdot 4 = 49 - 48 = 1\]
\[x_{1} = \frac{- 7 + \sqrt{1}}{2 \cdot 3} = \frac{- 7 + 1}{6} = \frac{- 6}{6} =\]
\[= - 1\]
\[x_{2} = \frac{- 7 - \sqrt{1}}{2 \cdot 3} = \frac{- 7 - 1}{6} = \frac{- 8}{6} =\]
\[= - \frac{4}{3}\]
\[3x^{2} + 7x + 4 =\]
\[= 3 \bullet (x + 1)\left( x + \frac{4}{3} \right) =\]
\[= (x + 1)(3x + 4).\]