# May i know (cos n pi ) with n to infinity is converges or diverges?

1. Feb 16, 2006

### teng125

may i know (cos n pi ) with n to infinity is converges or diverges??

may i know (cos n pi ) with n to infinity is converges or diverges??

2. Feb 16, 2006

### quasar987

Use the fact that if a sequence converges, the limit is unique, and the fact that if a sequence converges towards x, all subsequences converge towards x also.

Can you find 2 subsequences of {cos npi} that converges towards different numbers?

3. Feb 16, 2006

### teng125

is it -1 and +1 ??

4. Feb 16, 2006

### quasar987

Is there a doubt in your mind?

5. Feb 16, 2006

### teng125

yaya.pls explain to me

6. Feb 16, 2006

### quasar987

Is this in the context of an analysis class?

Are you familiar with the two theorems I quoted in my first post?

7. Feb 16, 2006

### teng125

no,what is subsequence??

8. Feb 16, 2006