Question

（6分）观察下面的变形规律：
 ＝1－； ＝－；＝－；……
解答下面的问题：
（1）若n为正整数，请你猜想＝                  ；
（2）证明你猜想的结论；
（3）求和：＋＋＋…＋ .

Answer 1

（1）·············································································· 1分
（2）证明：－＝－＝＝.····················· 3分
（3）原式＝1－＋－＋－＋…＋－
＝.································································· 5分

略