A= \(\frac{\left(x+1\right)^2}{(x-1)\left(x+1\right)}+\frac{(x-1)}{(x-1)\left(x+1\right)}-\frac{3x+1}{\left(x-1\right)\left(x+1\right)}\) \(đk:x\ne\pm1\)
= \(\frac{x^2+2x+1+x^2-2x+1-3x-1}{\left(x-1\right)\left(x+1\right)}\)
= \(\frac{2x^2-3x+1}{\left(x-1\right)\left(x+1\right)}\)
=\(\frac{2x^2-2x-x+1}{\left(x-1\right)\left(x+1\right)}\)
= \(\frac{\left(2x-1\right)\left(x-1\right)}{\left(x-1\right)\left(x+1\right)}\)
A= \(\frac{2x-1}{x+1}\left(tm\right)\)
\(\text{Đ}K:x\ne\pm1\)\(A=\frac{x+1}{x-1}+\frac{x-1}{x+1}-\frac{3x+1}{x^2-1}=\frac{\left(x+1\right)^2}{\left(x+1\right)\left(x-1\right)}+\frac{\left(x-1\right)^2}{\left(x+1\right)\left(x-1\right)}-\frac{3x+1}{x^2-1}=\frac{x^2-3x+1}{x^2-1}\)