\[ \begin{split} &\lim_{x \to 1}\left(\frac{2}{x^2-1}-\frac{1}{x-1}\right)=[\infty -\infty ]=\\[6pt] &=\lim_{x \to 1}\frac{1-x}{x^2-1}=\left[\frac{0}{0}\right]^H=\\[6pt] &=\lim_{x \to 1}\frac{-1}{2x}=\\[6pt] &=-\frac{1}{2} \end{split} \]