\[\frac{3x^{2}}{x^{2} - 1} - \frac{3x}{x - 1} = \frac{3x^{2}}{(x - 1)(x + 1)} -\]
\[- \ \frac{3x^{\backslash x + 1}}{x - 1} = \frac{3x^{2} - 3x^{2} - 3x}{(x - 1)(x + 1)} = \frac{- 3x}{x^{2} - 1} =\]
\[= \frac{3x}{1 - x^{2}}\]