若两条直线ax+2y+6=0与x+(a-1)y+(a2-1)=0平行,则a的取值集合是_.

问题描述:

若两条直线ax+2y+6=0与x+(a-1)y+(a2-1)=0平行,则a的取值集合是______.

∵两条直线ax+2y+6=0与x+(a-1)y+(a2-1)=0平行,直线ax+2y+6=0的斜率存在,∴x+(a-1)y+(a2-1)=0斜率也存在,两条直线ax+2y+6=0与x+(a-1)y+(a2-1)=0分别化为:y=−a2x−3,y=−1a−1x−(a+1).∴−a2=...