- #1

- 38

- 0

## Homework Statement

1. Determine whether the sequence is convergent or divergent. If it is convergent, find its limit.

a_n = 9^(n+1) / 10^n

Determine whether the series is convergent or divergent:

2. 1 / n(ln n)^2, series starts at n=2 and goes to infinity

3. Find the sum of the series:

[arctan (n+1) - arctan n], series starts at n=1 and goes to infninity.

## Homework Equations

## The Attempt at a Solution

1. I broke the problem down to: 9(9/10)^n, and said that as n->infinity the sequence also goes to infinity, so it's divergent. Need my method checked on that one.

2. Don't know about this one

3. Examples I've seen of these kinds of problems end up being a geometric series, so I just use a/1-r to find out sum of the series. But I don't think this applies here, so what else should I do?

Thanks for any help