x-（3x-1）≤x+2x-3x+1-x≤2-3x≤1x≥-1/3望采纳
x-（3x-1）≤x+2x-3x+1≤x+2-2x-x≤2-1-3x≤1x≥-1/3
x-（3x-1）≤x+2x-3x+1≤x+21-2≤3xx≥-1/3
