数学计算题(急用!!)
来源:百度知道 编辑:UC知道 时间:2024/07/02 19:19:05
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(1-1/2)*(1-1/3)*(1-1/4)*...*(1-1/999)*(1-1/1000)
[请写出过程,不用写太长]
(1+1/2+1/3+1/4)*(1/2+1/3+1/4+1/5)-(1+1/2+1/3+1/4+1/5)*(1/2+1/3+1/4)
[上面一道,用简便~]
麻烦了,今天就要用!!!!!
1*2+2*4+3*6+...+1002*2004
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1*5+2*10+3*15+...+1002*5010
[这道很重要! 答得好就有分喽!~~]
1,
可以看出这个式子是2000/10=200个
两个数一组,共200/2=100组
每组是20-10=10或2000-1990=10
列式子:10*(2000/20/2)=1000
2,
(1-1/2)*(1-1/3)*(1-1/4)*...*(1-1/999)*(1-1/1000)
=1/2*2/3*3/4*...*998/999*999/1000
=1/1000
如果你上面的是一道题:答案就是1000/(1/1000)=1000000
3,
(1+1/2+1/3+1/4)*(1/2+1/3+1/4+1/5)-(1+1/2+1/3+1/4+1/5)*(1/2+1/3+1/4)
=(1+1/2+1/3+1/4)*(1+1/2+1/3+1/4+1/5)-(1+1/2+1/3+1/4)-(1+1/2+1/3+1/4+1/5)*(1/2+1/3+1/4)
= (1+1/2+1/3+1/4+1/5)*[(1+1/2+1/3+1/4)-(1/2+1/3+1/4)]-(1+1/2+1/3+1/4)
=(1+1/2+1/3+1/4+1/5)-(1+1/2+1/3+1/4)
=1/5
附加题
1*2+2*4+3*6+...+1002*2004
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1*5+2*10+3*15+...+1002*5010
=2*(1*1+2*2+3*3+...+1002*1002)
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5*(1*1+2*2+3*3+...+1002*1002)
=2/5
10(200-199+198-197+...2+1)
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(1/2)*(2/3)*(3/4).....(998/999)*(999/1000)
10*100
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1/