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| Math Central | Quandaries & Queries |
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Question from terri, a parent: find the sum of the infinite geometric series 14 -7 +7/2 -7/4 +..... A. 7007/13 B. 2002 C. 28/3 D.5005/7 |
Hi Terri.
It looks like successive terms are multiplied by -1/2 each time.
Therefore, another way to write the terms is like this:
14 [-1/2]0 + 14 [-1/2]1 + 14 [-1/2]2 + 14 [ -1/2]3 + ...
Use the formula for the sum of an infinite geometric series S = a / (1 - r) where r is the common ratio between terms and a is the first element.
Hope this helps,
Stephen La Rocque.
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