1. Find the sum (2+1/2)^2 + (4+1/4)^2 +.......+ (2^n + 1/2^n ) .
2.. The infinite sum of a geometric sequence is 4 and the infinite sum of the cubes of its terms is equal to 192. Find the first term and the common difference.
ANS 1. 2n +4/3(4^n -1) + 1/3(1- 1/4^n)
ANS 2. a=6 , r = -1/2
Sequence
2007-09-23 1:28 am
回答 (1)
2007-09-23 3:43 am
✔ 最佳答案
(1)圖片參考：http://i117.photobucket.com/albums/o61/billy_hywung/Sep07/Crazyeqn19.jpg
(2)
圖片參考：http://i117.photobucket.com/albums/o61/billy_hywung/Sep07/Crazyeqn20.jpg
參考: My Maths knowledge
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