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标题: Find the minimum integer [打印本页]

作者: rongya 时间: 2007-5-30 05:48
标题: Find the minimum integer

(a+b/c).(e+d) where a, b,c,d,e are distinct integer from 1-9. What is the minimum integer answer we have from the equation above. And Justify your answer by proof why there is no smaller integer answer.

作者: yinyin 时间: 2007-5-30 08:04
标题: Welcome[@};-][>:D<]

Welcome!

To clarify the problem, I suggest rewriting it as:

"Consider (a+b/c)*(e+d) where a, b,c,d,e are distinct integers from 1-9. What is the minimum integer value we can obtain from the expression above? In addition, justify your answer by showing why there is no smaller integer answer. "

If my suggestion is correct, the answer should be 3 with (1) a+b = 4, c=8, and e+d = 6; or (2) a+b = 3, c=9, and e+d = 9; or (3) a+b = 3, c=7, and e+d = 7; or ......

本贴由[yinyin]最后编辑于：2007-5-30 2:51:36

作者: yinyin 时间: 2007-5-30 08:42
标题: 回复：Find the minimum integer

The reason for the answer being 3 is:

(a+b)*(d+e) is at least 21. If it can be exactly divided by an integer between 1 and 9, the quotient is at least 3.

作者: rongya 时间: 2007-5-30 17:07
标题: 回复：回复：Find the minimum integer

I think you made a mistake in understanding of this question. The question is (a +b/c), it is not (a+b)/c. So the answer is not 3.

作者: yinyin 时间: 2007-5-30 23:16
标题: 回复：Find the minimum integer

Sorry for my misunderstanding! If the dot in the expression is the multiplication operator, then the minimun value of the expression is 15, which is reached by (1+8/4)*(2+3) or (3+8/4)*(1+2).

作者: 开开心心 时间: 2007-5-31 03:13
标题: the minimum integer is 10

(2+4/8)*(1+3) =10

作者: ob 时间: 2007-5-31 03:21
标题: 回复：Find the minimum integer

(4+3/9)*(1+2)=13
(3+4/6)*(1+2)=11
(2+4/8)*(1+3)=10
(1+4/5)*(2+3)=9

Seems 9 is the minimum integer.

作者: yinyin 时间: 2007-5-31 03:51
标题: 回复：Find the minimum integer

(1+3/9)*(2+4)=8.

作者: ob 时间: 2007-6-1 08:44
标题: [:-Q]

作者: rongya 时间: 2007-6-1 22:47
标题: 回复：回复：Find the minimum integer

Finally, you got the right answer. But you know what the average time to do this question is only 80 seconds.

作者: Yalong 时间: 2007-6-2 03:20
标题: [:))][:))]

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