I'm just curios now, why I can't apply way that I was going...
and if I have sequence with just odd numbers .... (1+3+5+....+(2n-1) )/(n+1) I would have what ? I think I don't really see from what do u conclude that it's [n(n-1)/2]/n^2 ...
hehehe or I'm missing basic stuff here :(
April 23rd 2011, 11:57 PM
The top is still an arithmetic series, so you can use S = N(t_1 + t_N)/2 to simplify...
April 24th 2011, 12:03 AM
ah... OK :D
meaning that every time that I have infinite sequence like 1+2+3+... +n :D I have to look at it like series :D and go to nth partial sum :D
April 24th 2011, 05:34 AM
or simple use Stolz th that says ....
if you are given two sequences (x_n) and (y_n) and if
1° lim_(n->\infty) (x_n) = +\infty
2° y_(n+1) >= y_n