để 2 đt song song
\(\left\{{}\begin{matrix}2m+1=5\\-3m+1\ne1\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}m=2\\-3m\ne0\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}m=2\\m\ne0\end{matrix}\right.\Leftrightarrow m=2\)
Hai đường thẳng song song khi:
\(\left\{{}\begin{matrix}2m+1=5\\1\ne-3m+1\end{matrix}\right.\) \(\Leftrightarrow\left\{{}\begin{matrix}2m=4\\-3m\ne0\end{matrix}\right.\) \(\Rightarrow m=2\)
Để hai đường song song thì 2m+1=5
hay m=2