举个例子
1/(1*2)+1/(2*3)+1/(3*4)+......+1/(99*100)
=(1-1/2)+(1/2-1/3)+(1/3-1/4)+......(1/99-1/100)
=1-1/100
=99/100
题太多了,举例说明
1/2+1/6+1/12+1/20+1/30+1/42
=(1-1/2)+(1/2-1/3)+(1/3-1/4)+(1/4-1/5)+(1/5-1/6)+(1/6-1/7)
=1-1/2+1/2-1/3+1/3-1/4+1/4-1/5+1/5-1/6+1/6-1/7
=1-1/7
=6/7
1/2+1/6+1/12+1/20+1/30+1/42
=1-1/2+(1/2-1/3)+(1/3-1/4)+(1/4-1/5)+(1/5-1/6)+(1/6-1/7)
=1-1/7
=6/7