SOLUTION: How do I prove the following sequence is geometric? tn = 24 x (-1/2)n-1

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Question 590429: How do I prove the following sequence is geometric?
tn = 24 x (-1/2)n-1
Answer by Theo(13342) About Me  (Show Source):
You can put this solution on YOUR website!
if it has a common ratio then it's geometric.
if it has a common difference then it's arithmetic.
your equation is:
Tn = 24 x (-1/2)^(n-1)
your common ratio looks like it's (-1/2)
let's see how this works.
T1 = 24 * (-1/2)^0 = 24 * 1 = 24
T2 = 24 * (-1/2)^1 = 24 * -1/2 = -12
T3 = 24 * (-1/2)^2 = 24 * 1/4 = 6
T4 = 24 * (-1/2)^3 = 24 * -1/8 = -3
if you look at your number sequence you will see that the common ratio is (-1/2)
24 * (-1/2) = -12 * (-1/2) = 6 * (-1/2) = -3, etc.