\[\frac{(a - 1)(x + a)}{a - 3} = 0;\ \ x eq 3\]
\[(a - 1)(x + a) = 0\]
\[a = 1;\ \ \ \ \ \ x = - a\]
\[a = 1 \Longrightarrow x - любое.\]
\[a = - 3 \Longrightarrow нет\ решения.\]
\[a eq 1,\ a eq - 3 \Longrightarrow x = - a.\]