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问题: 数学

1/2+1/6+1/12+1/20+1/30......+1/98*99+1/99*100=

解答:

解:因为
1/2=1-1/2
1/6=1/2-1/3
1/12=1/3-1/4
...1/99*100=1/99-1/100
所以
1/2+1/6+1/12+1/20+1/30......+1/98*99+1/99*100
=1-1/2+1/2-1/3+1/3-1/4+...+1/99-1/100
=1-1/100
=99/100