Find the smallest positive term of the arithmetic sequence 123, 110, 97, 84, ......
請問這題怎樣做?
thx ^^
F.5 MATHS題
2007-10-08 5:01 am
回答 (1)
2007-10-08 5:14 am
✔ 最佳答案
First term, a = 123Common difference, d = 110 - 123 = -13
Let there are n terms
So, a + (n - 1)d = 0 (For the positive terms)
123 + (n - 1)(-13) = 0
-13n + 136 = 0
n = 10.46
n = 10
So, the smallest positive term is the 10th term
The smallest term
= 123 + (10 - 1)(-13)
= 6
參考: Myself~~~
收錄日期: 2021-04-23 17:19:01
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