[中學] 前n項和的表示

看板Math作者 (熱加熱)時間12年前 (2013/12/03 23:18), 編輯推噓0(0推 0噓 13→)
留言13則, 4人參與, 6年前最新討論串1/1
1 1 1 1 --------- + --------- + --------- + ...+ ----------------- a-b a^2-b^2 a^4-b^4 a^(2^n)-b^(2^n) 想請問此級數和的前n項的表示法要怎麼求 懇請指點 感恩!!! -- ※ 發信站: 批踢踢實業坊(ptt.cc) ◆ From: 59.104.37.160
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12/04 00:22, , 1F
不就sigma(1~n)(1/(a^(2^n)-b^(2^n)))?
12/04 00:22, 1F
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12/05 01:32, , 2F
1/(a-b)+1/(a^2-b^2)=[(a^2+b^2)+a+b+1]/(a^4-b^4)
12/05 01:32, 2F
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12/05 01:33, , 3F
correction
12/05 01:33, 3F
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12/05 01:34, , 4F
1/(a-b)+1/(a^2-b^2)=[(a^2+b^2)+a+b+1]/(a^2-b^2)
12/05 01:34, 4F
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12/05 01:36, , 5F
above+1/(a^4-b^4)=...
12/05 01:36, 5F
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12/05 01:37, , 6F
...=[(a^4+b^4)+a^2+b^2+a+b+1]/(a^4-b^4)
12/05 01:37, 6F
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12/05 01:39, , 7F
see the rule? move the dominator's part to the
12/05 01:39, 7F
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12/05 01:39, , 8F
numerator and the numerator could be separated
12/05 01:39, 8F
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12/05 01:40, , 9F
into the geometry seq. of a,b respectively. so
12/05 01:40, 9F
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12/05 01:41, , 10F
the numerator could expressed as a formula of n
12/05 01:41, 10F
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12/05 01:41, , 11F
and the dominator is simple.
12/05 01:41, 11F
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01/02 15:37, 7年前 , 12F
into the ge http://yofuk.com
01/02 15:37, 12F
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07/07 11:41, 6年前 , 13F
1/(a-b)+1/( https://moxox.com
07/07 11:41, 13F
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