标题: [数学] 再求助 [打印本页]

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作者: 哈哈爸    时间: 2009-5-2 09:46     标题: 再求助

2. How many whole numbers from 1 to 1000 can be expressed as the difference of the squares of two whole numbers? [ Note : 0 is a whole number.]

[Omission of essential working will result in loss of marks].

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作者: greenjyz    时间: 2009-5-3 22:00     标题: 回复 1#哈哈爸 的帖子

1000.

n^2-m^2 = (n-m)(n+m)

Let n-m=1, n+m=1,3,5,7,....
Let n-m=2, n+m=2,4,6,8,......

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作者: 哈哈爸    时间: 2009-5-3 22:30     标题: 回复 2#greenjyz 的帖子

多次得到您的帮助,谢谢greenjyz ..

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作者: greenjyz    时间: 2009-5-4 08:46     标题: 回复 3#哈哈爸 的帖子

别客气。.

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