- #1
anniecvc
- 28
- 0
Homework Statement
I have found the interval of convergence for the series
Ʃ (xn)/(3nn2) to be -3>x>3 and have tested +3 to break down to p series 1/n2 which converges.
However I am unsure of the negative endpoint of 3.
If I plug it in, the series looks like Ʃ(-3)n/(3nn2).
By alternating series test, the series should converge, but that is when the alternation is between -1 and 1. Here I have -3, which will alternate between larger and larger factors of 3 and -3. The denominator is 3n which given alone with the numerator would diverge, even though the denominator is multiplied by n2, I feel it is not sufficiently large enough for the limit to go to 0 as n -> ∞, since an exponential function grows more quickly than a quadratic.
I want to say it diverges, but don't have solid proof. Thoughts?
Last edited: