\[\frac{x - a}{x² - 5x + 6} = 0\]
\[x² - 5x + 6 \neq 0\]
\[x_{1} + x_{2} = 5\]
\[x_{1} \cdot x_{2} = 6\]
\[\Longrightarrow x_{1} \neq 3,\ \ x_{2} \neq 2.\]
\[x - a = 0\]
\[x = a.\]
\[При\ a = 3;\ \]
\[a = 2 \Longrightarrow нет\ решения.\]
\[При\ \ a \neq 3;a \neq 2 \Longrightarrow x = a.\]