作者chengwu2 (浩呆鄭)
看板NTUMath94
標題Re: 請問一題數學
時間Thu Jun 16 21:56:19 2005
※ 引述《chenjal (小隆)》之銘言：
: S=(1/1)^(1/2)+(1/2)^(1/2)+(1/3)^(1/2)+...+(1/1000000)^(1/2) 那是每一項開根號
: n<s<n+1 請問n=?
: 麻煩高手解答一下...謝謝
1000001
s= sigma n^(-1/2)
n=1
(1000001 (1000000
| n^(-1/2) dn < s < | n^(-1/2) dn +1
J 1 J 1
↑
此為積分符號XDDD
就想像n^(-1/2)的圖形
s會比從1積到1000001大
s會比1+從1積到1000000小
n^(-1/2)積分變成2n^(1/2)
故 2*(1000.xxx-1) < s < 2*(1000-1)+1
==>1998.xxx < s < 1999
n=1998
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◆ From: 61.226.44.175
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※ 編輯: chengwu2 來自: 61.226.44.147 (06/17 21:25)
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