\(m^2\left(x+2\right)-6=4m+x\)
\(\Leftrightarrow m^2x+2m^2-6-4m-x=0\)
\(\Leftrightarrow\left(m^2-1\right)x=6+4m-2m^2\)
PT vô nghiệm <=> \(\left\{{}\begin{matrix}m^2-1=0\\6+4m-2m^2\ne0\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}\left[{}\begin{matrix}m=1\\m=-1\end{matrix}\right.\\\left\{{}\begin{matrix}m\ne3\\m\ne-1\end{matrix}\right.\end{matrix}\right.\Rightarrow m=1\)