\(a,\Leftrightarrow\left\{{}\begin{matrix}m^2-4=0\\m-2\ne0\end{matrix}\right.\Leftrightarrow m=-2\\ b,\Leftrightarrow\left\{{}\begin{matrix}m-1=0\\2m\ne0\end{matrix}\right.\Leftrightarrow m=1\\ c,PT\Leftrightarrow\left[\left(m+1\right)^2-9\right]x+2m=0\\ \Leftrightarrow\left(m-2\right)\left(m+4\right)x+2m=0\)
PT vô nghiệm \(\Leftrightarrow\left\{{}\begin{matrix}\left(m-2\right)\left(m+4\right)=0\\2m\ne0\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}m=2\\m=-4\end{matrix}\right.\)
\(d,\Leftrightarrow\left\{{}\begin{matrix}m^2=0\\2m-1\ne0\end{matrix}\right.\Leftrightarrow m=0\)