hi,
how do i do (2n-1)!/(2n+1)!
salohcinseah,
I guess you din't get what veileen actually said.
See
$\displaystyle n! = 1. 2.\dots.(n-1).n$
So
$\displaystyle (2n-1)!= 1.2.\dots.(2n).(2n-1)$
Similarly
$\displaystyle (2n+1)!= 1.2.\dots.(2n-1).(2n).(2n+1)$
So, now divide both and see what remains.