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+....+1/98-1/99+1/99-1/100=1-1/100=99/100
=1-1/2+1/2-1/3+1/31/4+……+1/99-1/100=1-1/100=99/100
是1/(1*2)还是1*2/1
no
