1/1*2+1/3*4+1/5*6+...+1/2007*2008-1/1005-1/1006-1/1007-...-1/2008=?
问题描述:
1/1*2+1/3*4+1/5*6+...+1/2007*2008-1/1005-1/1006-1/1007-...-1/2008=?
答
1/1*2+1/3*4+1/5*6+...+1/2007*2008-1/1005-1/1006-1/1007-...-1/2008=(1+1/3+1/5+...+1/1003)-(1/2+1/4+1/6+...+1/1004)
会做了吧,不会再问我
答
1/3*4=1/3-1/4
1/5*6=1/5-1/6
然后逐项递减,明白?