1/1*2+1/2*3+……+1/48*49+1/49*50=?
问题描述：
1/1*2+1/2*3+……+1/48*49+1/49*50=?
答
1/1*2+1/2*3+……+1/48*49+1/49*50
=1-1/2+1/2-1/3+……+1/48-1/49+1/49-1/50
=1-1/50
=49/50