简便算法的练习题，我有道不会，帮帮啊

原式=1/2-1/2(1/3-1/3+1/5...-1/13+1/15 )
=1/2-1/3-1/30
=2/15
真萎,搞错两次,没脸见人了.

(1/2-1/3)-1/2(1/3-1/5)-1/2(1/5-1/7)...

回答即可得2分=1/2-1/3-1/3+1/5...-1/15+1/17
=1/2-2/3+1/17 ，回答被采纳则获得悬赏分以及奖励20分

1/2-1/3-1/3+1/5...-1/15+1/17
=1/2-2/3+1/17
=-11/102

裂项