(a)計算１＋３＋５＋．．．．．．．＋３９．
(b)計算１＋３＋５＋．．．．．．．＋１１．
根據(a)和(b)，計算１３＋１５＋１７＋．．．．．．＋３９．
解:
幫我計下Ｄ數
2008-08-20 7:21 am
回答 (2)
2008-08-20 7:25 am
１＋３＋５＋．．．．．．．＋３９
=15(1+39)/2
=300
１＋３＋５＋．．．．．．．＋１１
=6(1+11)/2
=36
１３＋１５＋１７＋．．．．．．＋３９
=(a)-(b)
=300-36
=264
2008-08-19 23:27:00 補充：
A １＋３＋５＋．．．．．．．＋３９
=20(1+39)/2
=400
sor~typed wrongly
2008-08-19 23:27:36 補充：
so the last one is 400-36 = 364
=15(1+39)/2
=300
１＋３＋５＋．．．．．．．＋１１
=6(1+11)/2
=36
１３＋１５＋１７＋．．．．．．＋３９
=(a)-(b)
=300-36
=264
2008-08-19 23:27:00 補充：
A １＋３＋５＋．．．．．．．＋３９
=20(1+39)/2
=400
sor~typed wrongly
2008-08-19 23:27:36 補充：
so the last one is 400-36 = 364
參考: nono
收錄日期: 2021-04-23 20:22:11
原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20080819000051KK03396