SOLUTION: the following sum is a partial sum in a geometric sequence, use this fact to evaluate the sum. 3+12+...+786432

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Question 438181: the following sum is a partial sum in a geometric sequence, use this fact to evaluate the sum.
3+12+...+786432

Answer by robertb(5830) About Me  (Show Source):
You can put this solution on YOUR website!

n = 9, and a%5B1%5D+=+3, r = 4

S+=+3%2A%28%281+-+4%5E10%29%2F%281-4%29%29+=+3%2A%28-1048575%2F-3%29+=+1048575