SOLUTION: Determine the sum of the series 3 + 12 + 48 + .... + 12288

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Question 1150955: Determine the sum of the series 3 + 12 + 48 + .... + 12288
Answer by Edwin McCravy(20064) About Me  (Show Source):
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a%5B1%5D=3 <-- first term

 <-- common ratio

a%5Bn%5D=a%5B1%5D%2Ar%5E%28n-1%29
12288=3%2A4%5E%28n-1%29
Divide both sides by 3
4096=4%5E%28n-1%29
4%5E6=4%5E%28n-1%29
6=n-1
7=n <-- number of terms

S%5Bn%5D=%28a%5B1%5D%28r%5En-1%29%29%2F%28r-1%5E%22%22%29
 <-- sum

Edwin