# Is it an Alternating Series?

## Homework Statement

Is this an alternating series : (-1)^n / ( arctan n ) ^ (n)

## Homework Equations

I know that the alternating series should have (-1) to any power, but also the signs should be - , + , - , + ..... or the opposit,

## The Attempt at a Solution

I am ok with this I know that for testing Con. Or Div. of this we should use the root test

But this series. But the problem is " Is this seris alternating or not"

Becasue if not it will be treated normally with a root test and it will Con.

For me I think that it is not "Alternating "

What do you think ?

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Dick
Homework Helper
Does 1/arctan(n)^n decrease to zero? That's what they want to you check.

mmm, do you mean the limit, if so no. It goes to inifity.

So, this is NOT an alternating sries, right ????

Dick
Homework Helper
No. 1/arctan(n)^n doesn't go to infinity. Tell me why you think it does.

ohhh, Ya , I remembred it goes to Pie/ 2
Right ?

Dick