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拜托各位大神帮忙解答一下～小女子不才！！！
1.The rate of a certain chemical reactionis directly proportional to the square of the concentration of chemical Apresent and
inversely proportional to the concentration of chemical B present.If the concentration of chemical B is increased by 100 percent,
which of thefollowing if closest to the percent change in the concentration of chemical Arequired to keep the reaction rate unchanged?
100% decrease/50% decrease/40% decrease/40% increase/50%increase
【答案】D
【思路】
題目意思是說化學物A的平方與此化學反應速率成正比
化學物B 與此化學反應速率成反比
所以B增加100% 換句話說B變成了兩倍所以反應速率變成1/2
要讓原本的速率不變所以A勢必要增加能讓速度變成兩倍去抵銷那1/2倍
得到算式會是2*1/2=1
A
的平方與速率成正比所以A平方就等於2 A就等於根號2=1.41...
換句話說增加了40%左右
2.If x 4+y 4=100,then the greatest possible value of x is between 0&3/ 3&6/6&9/9&12/12&15 答案： 3&6 把Y当成0计算
3.Is m + z >0?
1) m – 3z >0
2) 4z – m >0 (c)
两边相加得出Z>0,M>3Z>0
4.A certain stock exchange designateseach stock with a one-, two-, or three-letter code, where each letter isselected from the 26 letters of the alphabet. If the letters may be repeatedand if the same letters used in a different order constitute a different code,how many different stocks is it possible to uniquely designate with thesecodes?
2,951/8,125/15600/16302/18278
答案：18278【答案】E
【思路】題目有前提If the letters may be repeated and if the same letters used in a different order constitute a different code,
所以one letter-26種
two letters-26x26種
three letters-26x26x26種
total=18,278
5.Each of the students in a certain classreceived a singe grade of P,F, or I. what percent of the students in the classwere females?
1) Of those who received a P, 40 percentwere females
2) Of those who received either an F orI, 80 percent were males
(E)
6. For every positive integer n, functionh(n) is defined to be the product of all the even integers from 2 to n,inclusive, if p is the smallest prime factor of h(100)+1, then p is ?
Between 2 and 10
Between 10 and 20
Between 20 and 30
Between 30 and 40
Greaterthan 40
答案：Greaterthan 40
【答案】E
【思路】
假設h(100)+1最小因數是 n , n<50
例如47好了, 既然47是因數, 他就能整除h(100)+1
可是發現h(100)裡面有47的因數,可以整除那h(100)+1被47除的餘數為1,表示47不是h(100)+1的因數
同理去想小於50的其它因式也是會一樣的結果
所以h(100)+1的因式是在大於50外
重點在那50!, 假如小於50的質數是h(100)的factor,那就不會是h(100)+1的factor ,因為餘數會是1
7. On a certain sight-seeing tour, theratio of the number of women to the number of children was 5 to 2, what was thenumber of men on the sight-seeing tour?
(1) On the sight-seeing tour, the ratioof the number of children to the number of men was 5 to 11
(2) The number of women on thesight-seeing tour was less than 30
(C)
8. If n and y are positive integers and450y=n3, which of the following must be an integer?
I.y/3*22*5
II.y/32*2*5
III.y/3*2*55
None/I only/II only/III only/I II and III
答案：I only
450=3*3*2*5*5,因为N为整数，所以Y一定要包含3*2*2*5-- by 会员 喵嘎小皇妃 (2010/10/22 13:01:25)
这些题实在数学的破解版里有的，给你作参考了 |
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发表于 2010-10-22 13:01:25
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