1 câu trả lời
\[\begin{array}{l} m + \frac{1}{2}\left( {2x + 1} \right) + x = \left( {m + 1} \right)x - 3\\ \Leftrightarrow 2m + 2x + 1 + 2x = 2\left( {m + 1} \right)x - 6\\ \Leftrightarrow 4x + 2m + 1 - 2\left( {m + 1} \right)x + 6 = 0\\ \Leftrightarrow \left( {4 - 2m - 2} \right)x + 2m + 7 = 0\\ \Leftrightarrow \left( { - 2m + 2} \right)x + 2m + 7 = 0\,\,\left( * \right)\\ TH1: - 2m + 2 = 0 \Leftrightarrow m = 1\,thi\,\left( * \right)\,tro\,thanh\,9 = 0\left( {VN} \right)\\ TH2: - 2m + 2 \ne 0\,thi\,\left( * \right) \Leftrightarrow x = \frac{{2m + 7}}{{2m - 2}}\\ Vay\,neu\,m = 1\,thi\,pt\,VN\\ Neu\,m \ne 1\,thi\,pt\,co\,nghiem\,duy\,nhat\,x = \frac{{2m + 7}}{{2m - 2}} \end{array}\]