1分之1x2+1分之2x3+1分之3x4.+1分之99x100
问题描述：
1分之1x2+1分之2x3+1分之3x4.+1分之99x100
答
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
答
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]
=1-1/2+1/2-1/3+1/3-1/4+.+1/98-1/99+1/99-1/100
=1-1/100
=99/100