\[\frac{x - a}{(x - 5)(x + 6)} = 0,\]
\[x \neq 5,\ x \neq - 6\]
\[x - a = 0;\ \ \ \ x = a\]
\[a = 5;\ \ \ \]
\[a = - 6 \Longrightarrow нет\ решения.\]
\[a \neq 5;\ \ \ a \neq - 6 \Longrightarrow x = a.\]