The formula for the first part should be
Find a formula for
b. Also, show that if , then
a. By the Geometric Sum Formula,
Let , then substitute r back into (1) yields
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
I'm unsure what I am doing incorrectly for part (a).
Thank you for your time.