đkxđ: \(x\ne2\)
cách 1:
TH1:\(\left\{{}\begin{matrix}x+1>0\\x-2>0\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}x>-1\\x>2\end{matrix}\right.\Leftrightarrow x>2\)
TH2:\(\left\{{}\begin{matrix}x+1< 0\\x-2< 0\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}x< -1\\x< 2\end{matrix}\right.\Leftrightarrow x< -1\)
vậy x>2 hoặc x<-1
cách 2
x | -1 | 2 |
x+1 | - 0 + | \(|\) + |
x-2 | - \(|\) - | 0 + |
\(\frac{x+1}{x-2}\) | + 0 - | \(||\) + |
vậy x<-1 hoặc x>2