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Anonymous217
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Homework Statement
Determine whether the following series converges absolutely, converges conditionally, or diverges.
[tex]\sum_{n=1}^{\infty} \frac{(-1)^n}{n^3 - ln(n)}[/tex]
Homework Equations
The assortment of different tests.
The Attempt at a Solution
Okay, first of all, I tried using Alternating Series Test. This worked and the series satisfied all 3 conditions (decreasing, alternating, and limit as n approaches infinity = 0). This means the series must converge either conditionally or absolutely since I haven't eliminated the possibility of it converging absolutely yet.
So I take the absolute value of the series and if it converges, it's absolutely convergent.
If it diverges, then it's not absolutely convergent. Therefore, that means it's conditionally convergent because I already proved that it must converge in some manner.
So this is
[tex]\sum_{n=1}^{\infty} |\frac{(-1)^n}{n^3 - ln(n)}|[/tex]
[tex]=\sum_{n=1}^{\infty} |\frac{1}{n^3 - ln(n)}|[/tex]
Now how do I find that this series converges or diverges? I tried every test I'm aware of and each was inconclusive. I tried WolframAlpha and it said that the tests were inconclusive, but it gave a number.
Does this mean it absolutely converges? If so, how would I show my work?
I tried using the Direct Comparison test and compared the series with the absolute values to 1000/n^3. However, I'm not entirely sure if 1000/n^3 is greater than the absolute value series for all n terms.
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