SOLUTION: determine the number of terms n in each geometric series. Given that a1=3 r=6 and Sn=129

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Question 1136645: determine the number of terms n in each geometric series.
Given that a1=3 r=6 and Sn=129
Answer by greenestamps(13200) About Me  (Show Source):
You can put this solution on YOUR website!


a1=3; r=6....

S1 = 3

S2 = 3+18 = 21

S3 = 3+18+108 = 129

ANSWER: n=3