SOLUTION: A G.P has the second term as 9 and the fourth term is as 81.find the some of the first four term?
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Question 1191585: A G.P has the second term as 9 and the fourth term is as 81.find the some of the first four term?
Answer by greenestamps(13200) (Show Source): You can put this solution on YOUR website!
The 4th term 81 is the 3nd term 9, multiplied by the common ratio twice:
or
There are two possible answers to the problem.
(1) r=3; the first four terms are 3, 9, 27, 81; sum 120
(2) r=-3; the first four terms are -3,9,-27, 81; sum 60
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