Thu gọn \(\mathrm{B}=\frac{x+3}{x+1}-\frac{2 x-1}{x-1}-\frac{x-3}{x^{2}-1}\)

* Hướng dẫn giải

 \(\mathrm{MTC}=\mathrm{x}^{2}-1=(\mathrm{x}+1)(\mathrm{x}-1)\)

Khi đó:

\(\begin{aligned} &\mathrm{B}=\frac{(x+3)(x-1)-(2 x-1)(x+1)-(x-3)}{(x+1)(x-1)} \\ &\mathrm{B}=\frac{x^{2}+2 x-3-2 x^{2}+x+1-x+3}{(x+1)(x-1)} \\ &\mathrm{B}=\frac{1-x^{2}}{(x+1)(x-1)}=-1 \end{aligned}\)