4. Подробно. Спасибо. 50 б.

Решите задачу:

$\displaystyle \tt \left(\frac{2}{(1-x)^{2}}+\frac{1}{x^{2}-1}\right)\cdot (x-1)^{2}-\frac{3x}{x+1}=\left(\frac{2}{(1-x)^{2}}-\frac{1}{1-x^{2}}\right)\cdot (1-x)^{2}-\frac{3x}{1+x}=\\\\\\=\frac{2(1+x)-(1-x)}{(1-x)^{2}\cdot (1+x)}\cdot (1-x)^{2}-\frac{3x}{1+x}=\frac{3x+1-3x}{1+x}=\frac{1}{1+x};\\\\\\npu \ \ x=-1,5 \ \ \ \ \ \ \ \ \ \frac{1}{1+x}=\frac{1}{1-1,5}=-2;$