The formula for the first part should be
Problem:
Find a formula for
a.
b. Also, show that if , then
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a. By the Geometric Sum Formula,
(1)
Since (2)
Let , then substitute r back into (1) yields
(3)
Before I simplify this fraction, this formula doesn't seem right to me.
Suppose n=2 and x=2, then the equation (2) becomes
However, if you plug n =2 and x = 2 into equation (3) , then it becomes
But
(b) Since
I'm unsure what I am doing incorrectly for part (a).
Thank you for your time.