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呢個網係問題
a maths問題 關於factorial 有答案求詳細步驟
2008-12-22 3:35 am
回答 (2)
2008-12-22 4:17 am
✔ 最佳答案
1/(n+2)! - 1/(n+1)! - 1/n!= 1/(n+2)! - (n+2)/(n+2)! - (n+2)(n+1)/(n+2)!
= [1 - (n+2) - (n+2)(n+1)]/(n+2)!
= (1- n- 2- n^2- 3n- 2)/(n+2)!
= (-3- 4n- n^2)/(n+2)!
= - (n^2+ 4n+ 3)/(n+2)!
= - (n+1)(n+3)/(n+2)!
只要你明白 (n+2)! = (n+2)(n+1)! = (n+2)(n+1)n!
通分母問題即解決
參考: me
2008-12-22 4:39 am
收錄日期: 2021-04-23 20:36:19
原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20081221000051KK01532