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【纪念当年的帖子（2008）】高級數學纲要笔记
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发表于 3-11-2009 02:56 PM
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发表于 3-11-2009 03:15 PM
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回复 377# 天空之道 的帖子
其时问题说
Sn= -12,
S2n - Sn= 42,
注意sum of the first n term of the progression is -12 AND the next n term of the progression is 42
so, solve you get your answer |
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发表于 4-11-2009 09:54 PM
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回复 382# GeForceKAS 的帖子
对阿！！
我拿到99分哦！！ |
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发表于 5-11-2009 07:40 PM
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发表于 6-11-2009 12:05 AM
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这题我不明白~
Quetion:
the mass of student a school are normally distributed with a mean of 45kg and the varience is 25kg(square).Given that 35.2% of student have a mass less than m kg,find the value of m. |
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发表于 6-11-2009 12:33 AM
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原帖由 神探小露露 于 6-11-2009 12:05 AM 发表 
这题我不明白~
Quetion:
the mass of student a school are normally distributed with a mean of 45kg and the varience is 25kg(square).Given that 35.2% of student have a mass less than m kg,find the valu ...
献丑了，不知道对不对的。。。
Given that :
Mean= 45kg varience=25kg, s.d= 5kg Prabability= 35.2%= 0.352
P(X<m)= 0.352
By using formula,
P(Z<m-mean/s.d)=0.352
For Z<m-mean/s.d use distribution table....
P(Z< -0.38) = 0.352
(m-45/5) = -0.38
m-45 = -1.9
therefore : m = 43.1
Help me see whether answer right or not. I apologize if I am making mistake.. |
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楼主 |
发表于 7-11-2009 08:53 PM
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发表于 7-11-2009 11:16 PM
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发表于 8-11-2009 12:32 AM
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回复 391# yunsy 的帖子
1. tips: 当你画了三角形，不要割一半，from cos θ/2 = 1/ √1+p²，
we will get tan θ/2 = p ,是不是？
then， use formula tan θ = 2 tan θ/2 / 1-tan² θ/2....
14.
a.find dVB/dt and insert t =0
b.find the common part t of VB>0 and VA>0,同样for VB<0 and VA<0
c.first find SA=.∫ VA dt , then S2 - S1
d.也就说 SA= SB （SB= ∫ VB dt）
linear programming 的问题是整样？
对不起，如果我解释不大好的话 |
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发表于 8-11-2009 12:41 AM
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回复 391# yunsy 的帖子
oh，对差点忘了，
use sin 2θ=2 sin θ cos θ
so u must find sin and cos θ，
from (i), insert t = 2 and get tan θ= 。。。。。
then。。
got it？ |
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发表于 8-11-2009 11:26 AM
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回复 392# Log 的帖子
谢谢。。。原来如此
我了解了。。。
linear programming
它给1. bla bla bla
2. 就是那题 the maximum value of 3x+2y is twice the minimum value of 2x+3y
3. bla bla bla
我不会写第二的 |
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楼主 |
发表于 8-11-2009 01:10 PM
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回复 392# Log 的帖子
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谢谢 Log 代劳.. |
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楼主 |
发表于 8-11-2009 01:20 PM
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发表于 8-11-2009 03:44 PM
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回复 394# yunsy 的帖子
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不如你把整个写出来吧？ |
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发表于 8-11-2009 06:25 PM
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原帖由 天空之道 于 31-10-2009 07:12 PM 发表 
the first term of an arithmetic progression is -10 . Given that the sum of the first n term of the progression is -12 and the next n term of the progression is 42 , calculate the value of n.
结果。。。答案什么 |
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发表于 8-11-2009 07:12 PM
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回复 398# johnboy 的帖子
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n=3 |
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发表于 8-11-2009 07:19 PM
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发表于 8-11-2009 07:25 PM
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这里。。。 |
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发表于 8-11-2009 07:25 PM
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发表于 8-11-2009 07:26 PM
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