\[\frac{x^{2} - 4x + 3}{x - a} = 0;\ \ \ \ \ x \neq a\]
\[x^{2} - 4x + 3 = 0\]
\[x_{1} + x_{2} = 4;\ \ x_{1} \cdot x_{2} = 3\]
\[x_{1} = 3,\ \ x_{2} = 1.\]
\[1)\ \ a = x \Longrightarrow нет\ решения.\]
\[2)\ \ a \neq x \Longrightarrow x_{1} = 3;\ \ x_{2} = 1.\]