a) ĐKXĐ : \(\left\{{}\begin{matrix}x+1\ne0\\x-1\ne0\\x\ne0\end{matrix}\right.\) \(\Leftrightarrow\left\{{}\begin{matrix}x\ne-1\\x\ne1\\x\ne0\end{matrix}\right.\)
b) Rút gọn :
GT \(\Leftrightarrow\frac{x^2+1-x-1}{x+1}.\frac{4x-2x+2}{x\left(x-1\right)}\)
\(\Leftrightarrow\frac{x\left(x-1\right)}{x+1}.\frac{2\left(x+1\right)}{x\left(x-1\right)}=2\)