prep模考3道数学题

violetsapphire

ds:1. if m,n>0, is (m+x)/(n+x)>m/n?

a. m<n

b. x>0

答案：C

我选A

2. If m=根号4+三次根号下4+四次根号下4，then m is?

a.m<3   b.m=3  c.3<m<4  d.m=4  e. m>4

答案：E

不会做题思路

3. A certain stock exchange designates each stock with a one-,two-,or three-letter code,where each letter is selected from the 26 letters of the alphabelt. if the letters may be repeated and if the same letters used in a different order constitute a different code, how many different stocks is it possible to uniquely disignate with these codes?

a.2951   b.8125  c. 15600  d.16302  e18278

答案：E

我选A

以上3道题向大家请教了！

bobwangwbs

MM,数学要加强啦！

1：(m+x)/(n+x)-m/n=x(n-m)/n(n+x),剩下的就是判断x(n-m)，选C

这是个小公式，可以记住，用起来很方便的

2：m=根号4+三次根号下4+四次根号下4 〉2+1+1=4

逐个划范围，建议1-10的二次根号都背下来

3：股票分代码，26+26×26+26×26×26，每项结尾都是6，那么结果个位必为8，选E。不用算出结果

violetsapphire

看完楼上GG的解释，觉得好简单啊，真是笨死我啦！

第三题忽略了 if the letters may be repeated

谢谢啦！