- #1

ShizukaSm

- 85

- 0

## Homework Statement

[itex]\sum_{n=1}^{\infty}{(-1)^n*n}[/itex]

## The Attempt at a Solution

Well, this is a series I came upon when analyzing the endpoints of a particular power series, the thing is, my book says it's divergent by the

*Test for divergence*, however, I can't find this result, what I tried to do so far:

Alternating testing series: Of course, my first thought, the test fails because [itex]b_{n+1} > b_n[/itex], and not the opposite.

Then I tried the test for divergence:

[itex]\lim_{n->\infty}{(-1)^n*n}[/itex]

But I can't solve this limit, I could solve it without the [itex](-1)^n[/itex]. But I can't just "take out the term I don't like and solve it".

What am I doing wrong?

Thanks in advance.