\[x_{1} = 6;\ \ \ \ x_{2} = - \frac{1}{2}:\]
\[\left( x - x_{1} \right)\left( x - x_{2} \right) = 0\]
\[(x - 6)\left( x - \left( - \frac{1}{2} \right) \right) = 0\]
\[(x - 6)\left( x + \frac{1}{2} \right) = 0\]
\[x^{2} + \frac{1}{2}x - 6x - \frac{6}{2} = 0\]
\[x^{2} + \frac{1}{2}x - 6x - 3 = 0\ \ \ \ \ \ | \cdot 2\]
\[2x^{2} + x - 12x - 6 = 0\]
\[2x^{2} - 11x - 6 = 0.\]
\[Ответ:2x^{2} - 11x - 6 = 0.\]