搜搜考试网求解一道Gmat数据充分题
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求解一道Gmat数据充分题
If x and y are integers,is y an even integer?
(1) 2y – x = x^2 – y^2
(2) x is an odd integer.
条件（1）单独就是充分的
If x and y are integers,is y an even integer?
(1) 2y – x = x^2 – y^2
(2) x is an odd integer.
条件（1）单独就是充分的
From (1),we can know that x^2+x=y^2+2y.Because x is an odd integer,x^2 is an odd integer too.So the resuit of x^2+2 is an even integer.That is to say y^2+2y is an even integer.If y is an odd integer,y^2 is an odd integer while 2y is an even integer.When we plus y^2 and 2y,we will get an odd integer.It isn't correspond to the fact.So what we supposed just now is not true .Then,we can know that y is an even integer.其实题目不难的,建议你去西博海外听听他们免费的公益课.