求general term

點解冇"，" =w=
你將佢變左條算式...
你係想打1, - 1/3, + 1/5 ,- 1/7 ,+ 1/9 ,- 1/11 ,+ 1/13 ... ??
If yes, here is the answer.
An:
(-1)^n+1/2n-1

2008-01-10 14:18:38 補充：
留左括號...用電腦打好麻煩= =(-1)^(n 1)/(2n-1)

should be (-1)^{n+1) / (2n - 1)