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Homework Statement
First, I'd like to thank everybody a head of time. You guys have been an enormous help.
Second, I don't mind telling you that I'm finding sequences and series extremely frustrating. I usually pick this stuff up like nobody's business.
My problem is attached, but I will copy it down as I understand it.
[itex]
r = \frac{11}{24}
[/itex]
[itex]
\sum _{i=1} ^\inf nr^n
[/itex]
Mysteriously, this can be rewritten as
[itex]
\sum_{i=1} ^n ir^i = \frac{ nr^{n+2}  (n+1)r^{n+1} + r }{ (1  r)^2 }
[/itex]
Homework Equations
[itex]
\sum _{i=1} ^\inf nr^n \rightarrow
n \sum _{i=1} ^\inf r^n \rightarrow
n \frac{1}{1r}
[/itex]
The Attempt at a Solution
[itex]
\sum _{i=1} ^\inf nr^n \rightarrow
n \sum _{i=1} ^\inf r^n \rightarrow
n \frac{1}{1r}
[/itex]
[itex]
\frac{1}{1r}
[/itex]
This is a number greater than one,
[itex]
\frac{24}{13}
[/itex]
So as n goes to infinity, the number just gets bigger and bigger right? Diverges to infinite is, apparently, not the answer.
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