\(\Rightarrow x^3⋮x+1\\ \Rightarrow x^3+1-1⋮x+1\\ \Rightarrow\left(x+1\right)\left(x^2-x+1\right)-1⋮x+1\)
Mà \(\left(x+1\right)\left(x^2-x+1\right)⋮x+1\)
Do đó \(1⋮x+1\)
\(\Rightarrow x+1\inƯ\left(1\right)=\left\{-1;1\right\}\\ \Rightarrow x\in\left\{-2;0\right\}\)