數學問題：數論(20分)

2010-04-29 3:26 am

there are n integer, their sum is 0, product is n, Prove that n is divisible by 4.
要詳盡解釋.唔該.

回答 (5)

2010-04-29 6:41 am

✔ 最佳答案

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2010-04-28 22:41:42 補充：
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2010-05-06 12:08 am

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2010-04-29 8:00 am

nelson好勁...仲可以計到個數出黎~

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2010-04-29 6:16 am

2 is not divisible by 4 !!

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2010-04-29 4:47 am

This is wrong.

Take n = 2, let a, b be the 2 integers.
a + b = 0
ab = 2

a+b = 0 implies a = -b

implies 2 = ab = -a^2 < 0.

Contradiction!

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