\[\frac{x² + 3x}{x - 4} = \frac{x² - x}{4 - x}\]
\[ОДЗ:\ \ x \neq 4\]
\[\frac{x^{2} + 3x}{x - 4} = - \frac{x^{2} - x}{x - 4}\]
\[\frac{x² + 3x + x² - x}{x - 4} = 0\]
\[\frac{2x^{2} + 2x}{x - 4} = 0\]
\[2x^{2} + 2x = 0\]
\[2x(x + 1) = 0\]
\[x = 0\ \ \ \ \ \ \ \ \ x + 1 = 0\]
\[\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ x = - 1\]
\[Ответ:\ \ x = 0\ \ \ \ и\ \ \ x = - 1.\]