SOLUTION: what is the sum of the series of S7 for 5+10+20+40+..

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Question 619019: what is the sum of the series of S7 for 5+10+20+40+..
Answer by ewatrrr(24785) About Me  (Show Source):
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Hi

what is the sum of the series of S7 for 5+10+20+40+..

Geometric Series:  r = 2

a%5Bn%5D+=+5%282%29%5E%28n-1%29

S%5Bn%5D=+a%5B1%5D%28%281-r%5En%29%2F%281-r%29%29

S%5B7%5D=+5%28%281-2%5E7%29%2F%28-1%29%29 = 635