How do you find the sum of a geometric sequence whose first term is -160, whose last (nth) term is 5, and whose common ratio is -1/2?

1 Answer
Leland Adriano Alejandro
Feb 29, 2016

Sum =-105=−105

Explanation:

The numbers are
-160, 80, -40, 20, -10, 5−160,80,−40,20,−10,5

and these numbers may be obtained by multiplying the 1st term by r=-1/2r=−12and so forth and so on...

Add all the terms algebraically

Sum=-160+80-40+20-10+5=-105=−160+80−40+20−10+5=−105

Sum=-105=−105

God bless...I hope the explanation is useful..

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