设a,b,c都是实数,b≠c,且满足 则(a-b)(b-c)的值:A.小于零 B.等于零 C.大于零 D.无法确定

作者: tihaiku 人气: - 评论: 0
问题 设a,b,c都是实数,b≠c,且满足 则(a-b)(b-c)的值:
选项 A.小于零 B.等于零 C.大于零 D.无法确定
答案 A
解析 设a-b=x,b-c=y,则a-c=x+y,代入原式可得 由于 则可知x,y也是一个大于0,一个小于0或者x、y同时为0,但当x=y=0时,则a=b=c,与题干矛盾。故本题答案为A。

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