5x-3x=2m-6m+1 2x=-4m+1 x=(-4m+1)/2 -3<(-4m+1)/2 -4m+1>-6 4m<7 m<7/4 (-4m+1)/2≤2 -4m+1≤4 4m≥-3 m≥-3/4 所以-3/4≤m<7/4
