题目

直线l1:(m+2)x+(1-m)y=0,l2:(m-1)x+(2m+3)y+2=0,l1⊥l2,则m为(    )A.-1                B.1                 C.±1               D.- 答案:C解析:l1⊥l2A1A2+B1B2=0.
数学 试题推荐