SOLUTION: The first element of a geometric sequence is 1/8 and the eighth element is -16, what is the sixth element?

Question 1057964: The first element of a geometric sequence is 1/8 and the eighth element is -16, what is the sixth element?
Answer by rothauserc(4718) (Show Source): You can put this solution on YOUR website!
The definition of the nth term of a geometric sequence is
:
a(n) = a(0) * r^(n-1), where a(0) is the first term and r is the common ratio
:
we are given a(0) = (1/8) and a(8) = -16
:
-16 = (1/8) * r^(8-1)
:
r^7 = -128
:
r = -128^(1/7) = -2
:
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a(6) = (1/8) * (-2)^(6-1) = -4
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