1.(a+xb)=(3+2x,4-x) (a-b)=(1,5)两向量垂直,其数量积丛皮为0,即(3+2x,4-x)(1,5)=0,即3+2x+5(4-x)=0,解得x=23/32.y-3=1/3(x-2),化简y=1/3x+4/3 y-6=0(x-4),化简y=6注:这题都是基渗州差础题,可见阁下基本功不扎迹厅实