SOLUTION: the sum of first six term of gp is -136.5 . if the common ratio is -2 . find the third term

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Question 1140398: the sum of first six term of gp is -136.5 . if the common ratio is -2 . find the third term
Answer by ikleyn(52781)   (Show Source): You can put this solution on YOUR website!
.
Apply the formula for the sum of the first n terms of a GP


    S[6] =   =  = - 21a.


where "a" is the first term of the GP.


Therefore,  -21a = -136.5,  a =  = 6.5.


Then the third term of the GP is   =  = 26.     ANSWER


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