Posted by **Emily** on Tuesday, January 25, 2011 at 2:23pm.

Q: 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.

^Are there two answers, since the common ratio could be positive or negative?

- Math -
**drwls**, Tuesday, January 25, 2011 at 2:38pm
The ratio between successive terms is

(704/11)^(1/6) = 2 (or -2)

Yes, two answers are possible.

One series would be

11, 22, 44, 88, 176, 352, 704

and the other

11, -22, 44, -88, 176, -352, 704

You do the adding

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