Find the minimum integer

rongya

(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.

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yinyin

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 ...... www.ddhw.com     本贴由[yinyin]最后编辑于：2007-5-30 2:51:36

yinyin

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. www.ddhw.com

rongya

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. www.ddhw.com

yinyin

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).

开开心心

(2+4/8)*(1+3) =10 www.ddhw.com

ob

(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.

yinyin

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

ob

  

rongya

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

Yalong

一群大笨蛋,就楼主聪明!但要琢磨楼主的英文,恐怕８０秒还不够. www.ddhw.com