与x轴垂直的直线x=1显然不满足题意;设与x轴不垂直的直线为y=k(x-1)+2a到直线的距离d1=|k+2-3|/√(1+k²)b到直线的距离d2=|3k+2+5|/√(1+k²)d1/d2=|k-1|/|3k+7|=2即2|3k+7|=|k-1|2(3k+7)=k-1, 或2(3k+7)=1-k解得:k=-3, 或k=-13/6故直线为y=-3(x-1)+2=-3x+5或y=-13/6(x-1)+2=-13x/6+25/6