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奧數比賽題目

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1#
發表於 3/2/2005 09:34 PM | 只看該作者 回帖獎勵 |正序瀏覽 |閱讀模式
以下的題目是剛剛1星期前比賽的題目,我只抽一些難做的。

1)
Suppose p, q are positive integers and 96/35 > p/q > 97/36, find the smallest possible value of q.

2)
Let n be a natural number, the area of the triangle bounded by the line nx + (n+1)y = √2 and the two coordinate axes is S(n). If K = S(1) + S(2) + S(3) + ... + S(2005), find the value of K.

3)
Given that 60^a = 3 and 60^b = 5. If R = 12^[(1-a-b)/2(1-b)], find the value of R.

4)
Given that p, q and r are distinct roots of the equation x^3 - x^2 + x - 2 = 0. If Q = p^3 + q^3 + r^3, find the value of Q.

5)
If B is an integer and B > (√2 + √3)^6, find the smallest possible value of B.

6)
Given that the perpendicular distances from the point O to three sides of a triangle ABC are all equal to 2 cm and the perimeter of triangle ABC is equal to 20 cm. If the area of triangle ABC is equal to k cm^2, find the value of k.

7)
In Figure 1, ten people are sitting in a round table with sitting numbers 1, 2, 3, ..., 10 respectively. Each of them chooses an integer A, B, C, ..., J respectively and tells the people on his left and right about his chosen number. Then each of them calculates the average number of the chosen numbers of his two neighbourhoods and announces this average number. If all the announced average numbers are the same as the corresponding sitting number, find the value of F.
14#
發表於 15/2/2005 01:24 PM | 只看該作者
實在......好難.....我都做唔掂呀~(o個次7我去左個人同group~T.T)死喇~唔知入唔入到second round tim呀......
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13#
 樓主| 發表於 14/2/2005 12:05 PM | 只看該作者
Originally posted by smallpotato226 at 2005-2-14 11:56:
oic~
我就1定要用cal'tor la~~^^XD

cal'tor answer: 969.9989692

噢...撞o岩左...好野!
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12#
發表於 14/2/2005 11:56 AM | 只看該作者
oic~
我就1定要用cal'tor la~~^^XD

cal'tor answer: 969.9989692
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11#
 樓主| 發表於 14/2/2005 11:48 AM | 只看該作者
你去到呢一步都o岩~
跟住可以combine√2√3=√6
(√2 + √3)^6=485 + 198√6
跟住我記得一本maths書,教我點樣唔用cal'tor計root
就計到√6~2.45
(√2 + √3)^6~ 485+485.1~970
所以我估B=970
其實有d老作成份...
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10#
發表於 14/2/2005 11:38 AM | 只看該作者
幫我see see 7樓條數丫~~
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9#
 樓主| 發表於 14/2/2005 11:26 AM | 只看該作者
我上年只參加group
今年只參加individual
下年應該group+individual...
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8#
發表於 14/2/2005 11:24 AM | 只看該作者
Originally posted by oscar at 2005-2-13 08:35 PM:

係呀...
不過比賽時間有限,當時諗唔到咁多野出黎...
其實我又已經諗到第4-6題點做...

ng~
我D fd (參加奧數比賽果D)話佢一定輸
因為諗得慢

try:
5)
If B is an integer and B > (√2 + √3)^6, find the smallest possible value of B.

(√2 + √3)^6

=  √2^6    +  6  √2^5 √3    +  15  √2^4 √3^2  + 20 √2^3 √3^3   +  15  √2^2 √3^4   +  6  √2 √3^5   +   √3^6

= 8 +  24 √2√3  + 180 + 120 √2 √3   +  270  +  54  √2 √3   +   27

= 8 + 180 +  270  +   27 +  24 √2√3  + 120 √2 √3   +  54  √2 √3  

= 485 +  198 √2√3

之後ng識la~~XD
(o岩 ng o岩 ??)

[ Last edited by smallpotato226 on 2005-2-14 at 11:37 AM ]
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7#
 樓主| 發表於 13/2/2005 08:35 PM | 只看該作者
Originally posted by smallpotato226 at 2005-2-13 16:05:
第七題睇完answer又覺得ng係好難~~
只係煩左D~

係呀...
不過比賽時間有限,當時諗唔到咁多野出黎...
其實我又已經諗到第4-6題點做...
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6#
發表於 13/2/2005 04:05 PM | 只看該作者
第七題睇完answer又覺得ng係好難~~
只係煩左D~
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