\(3x^2+6x=0\)=>\(3x\left(x+2\right)=0\)=>x(x+2)=0=>\(\left[{}\begin{matrix}x=0\\x+2=0\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=0\\x=-2\end{matrix}\right.\)Câu trả lời: \(3x^2+6x=0\)=>\(3x\left(x+2\right)=0\)=>x(x+2)=0=>\(\left[{}\begin{matrix}x=0\\x+2=0\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=0\\x=-2\end{matrix}\right.\)