\[По\ теореме\ Виета:\]
\[x_{1} + x_{2} = - b;\ \ \ \ \]
\[x_{1} \cdot x_{2} = c.\]
\[x_{1} = 3 - \sqrt{31};\ \ x_{2} = 3 + \sqrt{31}:\]
\[x_{1} + x_{2} =\]
\[= 3 - \sqrt{31} + 3 + \sqrt{31} = 6;\]
\[x_{1} \cdot x_{2} = \left( 3 - \sqrt{31} \right)\left( 3 + \sqrt{31} \right) =\]
\[= 9 - 31 = - 22.\]
\[\Longrightarrow x^{2} - 6x - 22 = 0.\]