# Math Help - convegergent subsequence

1. ## convegergent subsequence

how do you find a convergent subsequence where

Sn = (-1) n(n+1) /2 ?

wont Sn tend to negative infinity no matter what the subsequence is?

thanks!

2. Originally Posted by alexandrabel90
how do you find a convergent subsequence where

Sn = (-1) n(n+1) /2 ?

wont Sn tend to negative infinity no matter what the subsequence is?

thanks!

Yes...unless it is NOT -1 but rather $(-1)^n$ or something like that. Check it, otherwise the question's pretty trivial.

Tonio