1x2/1+2x3/1+3x4/1+……+98x99/1+99x100/1=?
问题描述:
1x2/1+2x3/1+3x4/1+……+98x99/1+99x100/1=?
答
1x2/1+2x3/1+3x4/1+……+98x99/1+99x100/1
=1/1-1/2+1/2-1/3+1/3-1/4+...+1/98-1/99+1/99-1/100
=1-0-0-...-0-1/100
=99/100