ĐKXĐ: \(\left\{{}\begin{matrix}x-m\ge0\\2x-m-1\ge0\end{matrix}\right.\) \(\Rightarrow\left\{{}\begin{matrix}x\ge m\\x\ge\frac{m+1}{2}\end{matrix}\right.\)
\(\Rightarrow\left\{{}\begin{matrix}m\le0\\\frac{m+1}{2}\le0\end{matrix}\right.\) \(\Rightarrow m\le-1\)