\[a² - 13a + 22 = 0\]
\[\left\{ \begin{matrix} a_{1} + a_{2} = 13 \\ a_{1} \cdot a_{2} = 22\ \ \\ \end{matrix} \right.\ \]
\[a_{1} = 2;\ a_{2} = 11:\]
\[\Longrightarrow a^{2} - 13a + 22 =\]
\[= (a - 2)(a - 11).\]