# Does this series converge.

rcmango

## Homework Statement

Does the series infinity n(sin(1/n)) converge?
E
n=1

n

and

sin(1/n)

## The Attempt at a Solution

The equation sin(1/n) looks familiar, maybe i could use the squeeze theorem?

something like -1 <= sin(1/n) <= 1

i'm not sure where to go after this though, or if I'm even on the right track?
thankyou.

Homework Helper
Gold Member
Dearly Missed
First check:
Does the general term go to zero as n goes to infinity?

Homework Helper
Yes You could use the squeeze theorem and get -|x|< sin(1/x) < |x|, but that doesn't seem the help you much. Do what arildno said, maybe a few other convergence tests, try using Taylor Series? I'd say it does, but can't show you right now.

Homework Helper
Since this is not an alternating series, then only answering the question posed by Arildno is enough to solve the problem.

Daniel.

lkh1986
There is a general formula: as x approaches 0, (sin x)/x approaches 1. So you can apply this in your question. Let n=1/x, then you modify the equation, then you will get the answer that the series diverge, since the series does not have a sum.

rcmango

Last edited:
rcmango
First check:
Does the general term go to zero as n goes to infinity?

yes. i would say as n goes to infinity, it approaches 0.
the reasoning is because starting with small numbers it gets larger around .01745...

don't know where to go from here.

thanks for all the feedback, i found it all useful.

d_leet
yes. i would say as n goes to infinity, it approaches 0.
the reasoning is because starting with small numbers it gets larger around .01745...

don't know where to go from here.

thanks for all the feedback, i found it all useful.

Numbers at a certain point don't really tell you much about the behavior at infinity. Take the limit of the terms as n goes to infinity, if it isn't 0 what can you say about the series?

rcmango
Numbers at a certain point don't really tell you much about the behavior at infinity. Take the limit of the terms as n goes to infinity, if it isn't 0 what can you say about the series?

that it diverges.

theperthvan
that it diverges.

yes it does