\(\Leftrightarrow\left(m^2-5m+6\right)x-m^2+2m=0\)
PT vô nghiệm \(\Leftrightarrow\left\{{}\begin{matrix}m^2-5m+6=0\\-m^2+2m\ne0\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}\left[{}\begin{matrix}m=3\\m=2\end{matrix}\right.\\\left\{{}\begin{matrix}m\ne0\\m\ne2\end{matrix}\right.\end{matrix}\right.\Leftrightarrow m=3\)