x+5, 3x+2, 5x-1, ..., 31x-40
更新1:
What is the origin of 31x - 40
更新2:
第3行.... 點計到31x - 40
F5 Maths
2010-09-23 1:28 am
Find the number of terms in each of the following arithmetic sequences.
x+5, 3x+2, 5x-1, ..., 31x-40
x+5, 3x+2, 5x-1, ..., 31x-40
回答 (1)
2010-09-23 1:38 am
✔ 最佳答案
Common difference = 3x+2 - (x+5) = 2x - 3The gernal term T(n) = x+5 + (2x-3)(n-1)Let T(k) be 31x - 40 , x+5 + (2x-3)(k-1) = 31x - 40(2x-3)(k-1) = 30x - 45k - 1 = (30x - 45)/(2x - 3)k - 1 = 15k = 1616 terms2010-09-22 18:40:57 補充：
可不可用中文問?唔明
2010-09-22 19:25:53 補充：
31x - 40 is the last term which is given by your question.
只要找出31x - 40 是第幾個 term (T(k)) ,就知有幾個 terms 。
k = 16 , 所以有 16 個 terms 。
收錄日期: 2021-04-21 22:22:32
原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20100922000051KK00751