Find the general term and explain how and why.
4,-16,64,-256...
F.1 math (general term of sequence)
2008-10-12 11:54 pm
回答 (2)
2008-10-13 12:27 am
✔ 最佳答案
4,-16,64,-256... Starting from the second term, each term is -4 times of the previous term and the general term is
-(-4n)
(Because the first number, 4, is positive and it's equal to -(-4))
2008-10-13 17:49:58 補充：
sorry
The answer is -(-4)^2
2008-10-13 17:50:19 補充：
nonono
-(-4)^n
參考: me
2008-10-14 12:46 am
4,-16,64,-256...
T(2)/T(1)=-16/4=-4
T(3)/T(2)=64/-16=-4
So 4,-16,64,-256... is a geometric sequence
The first term a=4
The common ratio r=-4
The General term T(n):
ar^(n-1)
=4(-4)^(n-1)
=-(-4)(-4)^(n-1)
=-(-4)^n
T(2)/T(1)=-16/4=-4
T(3)/T(2)=64/-16=-4
So 4,-16,64,-256... is a geometric sequence
The first term a=4
The common ratio r=-4
The General term T(n):
ar^(n-1)
=4(-4)^(n-1)
=-(-4)(-4)^(n-1)
=-(-4)^n
參考: 自己
收錄日期: 2021-04-13 16:13:00
原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20081012000051KK01364