(文)若点(1,a)到直线x-y+1=0的距离是,则实数a为A.-1            B.5

(文)若点(1,a)到直线x-y+1=0的距离是,则实数a为

A.-1            B.5                  C.-1或5        D.-3或3

 

答案

答案:

(文)C  由点到直线的距离得,解得a=-1或5.

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