1/1*2*3+1/2*3*4+1/3*4*5 省略 1/98*99*100*是乘号要最简便的,这个好象有点复杂!
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![1/1*2*3+1/2*3*4+1/3*4*5 省略 1/98*99*100*是乘号要最简便的,这个好象有点复杂!](/uploads/image/z/565817-41-7.jpg?t=1%2F1%2A2%2A3%2B1%2F2%2A3%2A4%2B1%2F3%2A4%2A5+%E7%9C%81%E7%95%A5+1%2F98%2A99%2A100%2A%E6%98%AF%E4%B9%98%E5%8F%B7%E8%A6%81%E6%9C%80%E7%AE%80%E4%BE%BF%E7%9A%84%EF%BC%8C%E8%BF%99%E4%B8%AA%E5%A5%BD%E8%B1%A1%E6%9C%89%E7%82%B9%E5%A4%8D%E6%9D%82%EF%BC%81)
1/1*2*3+1/2*3*4+1/3*4*5 省略 1/98*99*100*是乘号要最简便的,这个好象有点复杂!
1/1*2*3+1/2*3*4+1/3*4*5 省略 1/98*99*100
*是乘号
要最简便的,这个好象有点复杂!
1/1*2*3+1/2*3*4+1/3*4*5 省略 1/98*99*100*是乘号要最简便的,这个好象有点复杂!
1/1*2*3+1/2*3*4+1/3*4*5 +.+1/98*99*100
=1/2*[2/(1*2*3)+2/(2*3*4)+...+2/(98*99*100)]
=1/2*[(3-1)/(1*2*3)+(4-2)/(2*3*4)+...+(100-98)/(98*99*100)]
=1/2*[3/(1*2*3)-1/(1*2*3)+4/(2*3*4)-2/(2*3*4)+...+100/(98*99*100)-98/(98*99*100)]
=1/2*[1/(1*2)-1/(2*3)+1/(2*3)-1/(3*4)+...+1/(98*99)-1/(99*100)]
=1/2*[1/2-1/9900]
=4949/19800