# Math

Determine the sum of the first seven terms of a geometric series in which the first term is 11 and the seventh term is 704.

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1. a = 11
ar^6 = 704 = 11*64
so, r^6 = 64, meaning r = ±2
As usual, the sum of n terms is
Sn = a(r^n-1)/(r-1)

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