作者  dqIpb (dqipb)                                               看板  Math 
 標題  Re: [中學]  100 教甄 << 高師大 附中 >>                                 
 時間  Sun Aug 14 18:57:12 2011                                               
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※ 引述《diow1 (小玉)》之銘言：
: 1/                                  2      2           2
:   a1 , a2 ,...a10  屬於 N        (a1 +1)(a2 +1)....(a10 +1)
:                             求 -------------------------------的最小值 ?
:                                      a1a2a3....a10
:                            1
: 2/若 S= __________________________________________求 S 小數點後第一位數字 ?
:            __1__ + __1__ + ... + __1__ + __1__
:             429     430           499     500
:   學校給的答案 1/   1024
:                2/    4

           1/S=(1/429+1/500)+(1/430+1/499)+...+(1/464+1/465)

              =929[ 1/(429*500) + 1/(430*499) + ... + 1/(464*465) ]

=> 929*36/(429*500) > 1/S > 929*36/(464*465)

=> 6.417... = 429*500/(929*36) < S < 6.451... = 464*465/(929*36)

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推 diow1       : 哇 咧 ! 酷 ...感恩                                08/14 19:27