\[\frac{6}{x² + x} - \frac{x - 6}{x^{2} - x} + \frac{10}{x^{2} - 1} = 0\]
\[- x^{2} + 21x = 0\]
\[- x(x - 21) = 0\]
\[x = 0\ (не\ подходит),\ \]
\[x - 21 = 0,\ \ x = 21\]
\[Ответ:x = 21.\]