2,6,18,54....求n?
請問怎樣列式?
雖知道前一個位乘3,但不懂列式.
再問此類問題有什麼固定法列式?
謝謝
數學問題-n Term
2014-10-26 2:41 am
回答 (5)
2014-10-26 4:16 pm
✔ 最佳答案
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2,6,18,54....
a1(首項)=2
q(公比)=3
一般項:an= 2*3^ (n-1)
2014-10-26 11:11 pm
1st term = 2/3x((1)3)=2
2nd term = 2/3x((2)3)=6
3rd term = 2/3x((3)3)=18
General term =nth term
=2/3x((n)3)
2014-10-26 15:14:30 補充：
固定法列式:
1st term =........=..........
2nd term =........=..........
3rd term =........=.........
General term=nth term
=........
2nd term = 2/3x((2)3)=6
3rd term = 2/3x((3)3)=18
General term =nth term
=2/3x((n)3)
2014-10-26 15:14:30 補充：
固定法列式:
1st term =........=..........
2nd term =........=..........
3rd term =........=.........
General term=nth term
=........
參考: me ^.^
2014-10-26 7:00 am
嘗試 (第2個)/(第1個) 係唔係 = (第3個)/(第2個)
或 (第2個) - (第1個) 係唔係 = (第3個) - (第2個)
等等方法去思考個第n Term
或 (第2個) - (第1個) 係唔係 = (第3個) - (第2個)
等等方法去思考個第n Term
2014-10-26 6:20 am
謝謝回答.但這類問題有何方法去構思答案?
2014-10-26 3:20 am
Nth term=2*3^(n-1)
收錄日期: 2021-04-15 17:01:31
原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20141025000051KK00101