=1-1/2 1/2-1/3 1/3-1/4 ...... 1/99-1/100
=1-1/100
=99/100
原式=1-1/2+1/2-1/3+3/1-1/4+....+1/99-1/100
=1-1/100
=99/100
用裂项法:解原式=(1-1/2)+(1/2-1/3)+(1/3-1/4)+...+(1/99-1/100)=1-1/100=99/100
原式=1-2|1+2|1-3|1+3|1-4|1+……+99|1-100|1=1-100|1=100|99望采纳
1/n(n+1)=1/n-1/(n+1),裂项相消