1/1*2+1/2*3+1/3*4+..........+1/98*99+1/99*100
=1-1/2+1/2-1/3+1/3-1/4+……+1/99-1/100
中间抵消
=1-1/100
=99/100
解:因为:1/n-1/(n+1)=1/[n(n+1)]
所以,
1/(1×2)+1/(2×3)+1/(3×4)+..........+1/(98×99)+1/(99×100)
=1/1-1/2+1/2-1/3+1/3-1/4+……+1/98-1/99+1/99-1/100
=1/1-1/100
=1-1/100
=99/100
原式=1-1/2+1/2-1/3+1/3-1/4…+1/98-1/99+1/99-1/100=1-1/100=99/100
解 原式=1-1/2+1/2-1/3+1/3-1/4.......+1/99-1/100
=1-1/100
=99/100