Question

\(x^3+x=0\)

Answer 1

\(x^3+x=0\)

\(\Rightarrow x\left(x^2+1\right)=0\)

\(\Rightarrow x=0\)(do \(x^2+1\ge1>0\))

Answer 2

\(\Rightarrow x\left(x^2+1\right)=0\Rightarrow\left[{}\begin{matrix}x=0\\x^2=-1\left(vô.lí\right)\end{matrix}\right.\Rightarrow x=0\)