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Mutaja
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Homework Statement
Check if the series below converge.
a) $$\sum_{n = 1}^\infty \frac{n}{2n^2 - 1}$$
b) $$\sum_{n = 2}^\infty (-1)^n \frac{2n}{n^2 - 1}$$
Homework Equations
The Attempt at a Solution
For a).
The series converge if the sum comes up to a finite value. If not, and it goes to positive or negative infinity, it diverges. That's all good.
I've also learned that if the common ratio is below 1 and greater than 0, the series will converge. The common ratio, as I understand it, is the expression that's containing n.
For instance, if the series is ## 2^n ##, then the common ratio is 2. If you have a more advanced expression, and you obtain a constant, that constant is not part of the common ratio.
What I'm confused with here, I believe, is basic algebra. Is there a way I can re-write my expression ([itex]\frac{n}{2n^2 - 1}[/itex]) to obtain the common ratio?