maths求數形
求數形
(1) 98,91,84,77,70,...
(2) 2,13,24,35,46,...
(3)1/3,1/9,1/27,1/81,...
/ = over
maths求數形
2007-10-23 6:39 am
回答 (1)
2007-10-23 9:11 am
✔ 最佳答案
1) n/2 [ 2(98) + (n-1)7 ]=n/2 [ 2(98) + 7n - 7 ]
=98n + (7n^2)/2 - (7n)/2
=(7n^2)/2 + 28n
2) n/2 [ 2(2) + (n-1)11 ]
=n/2 [ 2(2) + 11n - 11 ]
=2n + (11n^2)/2 - (11n)/2
=(11n^2)/2 + (7n)/2
3) (1/3) (1/3)^(n-1)
=1/3^n
參考: myself
收錄日期: 2021-04-16 17:00:43
原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20071022000051KK04373