我又來問數學問題了高中數學與階乘有關的題目

2010-06-24 8:38 am
(1X1!+2X2!+3X3!+4X4!+5X5!+......+2008X2008!)/2008的餘數是多少?

回答 (1)

2010-06-24 8:44 am
✔ 最佳答案
k*k!=(k+1)!-k!
so,Σ[k=1~2008] k*k!=[k=1~2008] {(k+1)!-k! }
= 2!-1!+ 3!-2!+...+2009!- 2008!
=2009!- 1

2009!= 2008* 2009*2007!= 2008a
so, 2009!-1= 2008a-1=2008(a-1)+ 2007

thus, the remainder is 2007


收錄日期: 2021-05-02 10:12:36
原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20100624000010KK00321

檢視 Wayback Machine 備份