1/1乘2乘3+1/2乘3乘4+...+1/98乘99乘100=

学习 时间:2026-04-08 23:24:24 阅读:931
1/1乘2乘3+1/2乘3乘4+...+1/98乘99乘100=

最佳回答

年轻的红酒

热情的春天

2026-04-08 23:24:24

1/(1*2*3)+1/(2*3*4)+。。。+1/(98*99*100)=(1/2)[1/(1*2)-1/(2*3)]+(1/2)[1/(2*3)-1/(3*4)]+。。。+(1/2)[1/(98*99)-1/(99*100)]=(1/2)[1/(1*2)]-(1/2)[1/(2*3)]+(1/2)[1/(2*3)]-(1/2)[1/(3*4)]+。。。+(1/2)[1/(98*99)]-(1/2)[1/(99*100)]中间的全部互相抵消,所以=(1/2)[1/(1*2)]-(1/2)[1/(99*100)]=4949/19800

最新回答共有2条回答

  • 炙热的台灯
    回复
    2026-04-08 23:24:24

    1/(1*2*3)+1/(2*3*4)+。。。+1/(98*99*100)=(1/2)[1/(1*2)-1/(2*3)]+(1/2)[1/(2*3)-1/(3*4)]+。。。+(1/2)[1/(98*99)-1/(99*100)]=(1/2)[1/(1*2)]-(1/2)[1/(2*3)]+(1/2)[1/(2*3)]-(1/2)[1/(3*4)]+。。。+(1/2)[1/(98*99)]-(1/2)[1/(99*100)]中间的全部互相抵消,所以=(1/2)[1/(1*2)]-(1/2)[1/(99*100)]=4949/19800

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