SOLUTION: Find the explicit formula for the geometric sequence with a9 = 128 and r = 2.

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Question 977416: Find the explicit formula for the geometric sequence with a9 = 128 and r = 2.
Answer by Cromlix(4381) About Me  (Show Source):
You can put this solution on YOUR website!
Hi there,
Using the formula:
a(n) = a(1)(r)^n -1
a(9) = a(1)*(2)^8 = 128
a(1)* 256 = 128
a(1) = 0.5
Explicit formula =
a(n) =0.5*(r)^n-1
Hope this helps:-)