求無窮等比級數1/(2^0.5+1)+1(2+2^0.5)+1/(8^0.5+2)+.......?
回答 (2)
2018-12-01 12:55 am
首項 a = √2 -1
第二項 b = (2-√2)/2
公比 r = b/a = √2 / 2
S = a/(1-r) = (√2-1)/[1-(√2/2)] =√2
第二項 b = (2-√2)/2
公比 r = b/a = √2 / 2
S = a/(1-r) = (√2-1)/[1-(√2/2)] =√2
2018-11-27 6:04 pm
題目是不是有打錯?
收錄日期: 2021-04-11 22:21:32
原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20181126151020AAa1nFt