1/6n(n+1)(n+2)?
回答 (2)
2016-02-12 6:40 am
1/6n(n+1)(n+2) 這式化了。
2016-02-13 3:54 am
n(n+1)(n+2)/6
=n(n^2+2n+n+2)/6
=n(n^2+3n+2)/6
=(n^3+3n^2+2n)/6
=n(n^2+2n+n+2)/6
=n(n^2+3n+2)/6
=(n^3+3n^2+2n)/6
收錄日期: 2021-04-18 14:27:50
原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20160211224009AAXfjpx