# Convergance and Divergence Could someone go over a routine to help determine them?

1. Oct 14, 2011

### tamintl

Hey there..

Basically I'm struggling with convergence and divergence of series.

I can see if converges and diverges by common sense and thinking through in my head but I struggle to write it down. The definitions in books seem confusing.

Are there any steps I can systematically do every time which will help me determine on paper if the said series div. or conv.?

For example a basic typical question in my course is like the following:

as n ---> infinity

$\sum$ (n^2 - 1) / (n^4 + 1)

Some detailed exlanation in basic language would be greatly appreciated

Regards
Tam

2. Oct 14, 2011

### spamiam

Re: Convergance and Divergence.. Could someone go over a routine to help determine th

There are many different tools to test the convergence of a series, the most common probably being the comparison test, the integral test, the ratio test, and the nth root test. Here's a link with a big list: http://www.math.hmc.edu/calculus/tutorials/convergence/

In your particular example, I think comparison with the series $\sum_{n=1}^\infty \frac{1}{n^2}$ is the easiest test to use.

3. Oct 15, 2011