SOLUTION: The sum of first 6 terms of the geometric sequence is 1,-2,4,-8,....is?

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Question 978567: The sum of first 6 terms of the geometric sequence is 1,-2,4,-8,....is?

Answer by ikleyn(52790)   (Show Source): You can put this solution on YOUR website!

The first term of this geometric progression   = ,
and the ratio is   = .

The formula for the sum of first  n  terms of a geometric progression is

=

(see everythere,  for example,  in the lesson  Geometric progressions  in this site).
Substitute here    and   n=6,   and you will get

= = = = = = = = .


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