\[x² - 6x + 8 = 0\ \]
\[x_{1} + x_{2} = 6\]
\[x_{1} \cdot x_{2} = 8 \Longrightarrow x_{1} = 2;\ \ x_{2} = 4\]
\[Ответ:x_{1} = 2;\ \ x_{2} = 4.\]