find the terms inserted.
更新1:
自由自在:我想問點解要n+2?
F.6 Arithmetic sequence, help!
2011-09-11 7:02 pm
insert some terms between 8 and 76 such that they form an arithmetic sequence and the sum of all terms of this sequence just exceeds 200.
find the terms inserted.
find the terms inserted.
回答 (1)
2011-09-11 7:26 pm
✔ 最佳答案
Suppose we insert n terms, so all together there are n+2 termsAverage of all terms= (8+76)/2=42Sum=(n+2)(42)>200 => n+2>4.76 => n>2.76 => n≥3So we need to insert at least 3 terms=>total number of term=58+(5 – 1)d = 76 => d=17So the terms inserted are 8+17, 8+34 and 8+51 or 25,42 and 592011-09-11 22:33:39 補充：
原本得8及76兩個term加入n個,不就是n+2個嗎?
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