SOLUTION: In a geometric progression, the common ratio is -2 and the 8th term is -640. What is the first term?
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Question 922690: In a geometric progression, the common ratio is -2 and the 8th term is -640. What is the first term?
Answer by srinivas.g(540) (Show Source): You can put this solution on YOUR website!
Formula :n th term =
where a = first term
r= common ratio =-2
we need to figure out 8 th term. so put n=8 in the above equation
8 th term =
divide with -128 on both sides
=
5= a
result : first term (a) =5
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