a question from Prep...! thanks

106. If x and y are integers, is xy even?
(1) x = y + 1
(2)
x/y
is an even integer.

answer is D from Prep

why (1) is right. if Y=0, X=1, then xy is 0, which is not even. why we dont consider 0 here??? thanks

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rudder86发表于 2010-11-20 21:22 | 只看该作者

0是偶数

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IMARCUS发表于 2010-11-21 06:41 | 只看该作者

LZ should think this way: If X = Y + 1, then X and Y are consecutive intigers. Among a pair of consecutive intigers, one of them must be an even number.

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