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标题: 一道PREP上的题~~牛想不通~~~ [打印本页]

作者: xionghuixh    时间: 2009-6-26 06:57     标题: 一道PREP上的题~~牛想不通~~~

r和m是数轴上的两个数,问r的大小

1 the distance between m and 0 are 3 times the distance between m and 0

2 12 is the halfway between m and r

我选了C~~答案是E~~~我想来想去觉得是C丫~~~


作者: BruceNornia    时间: 2009-6-26 07:55

题目也很奇怪 少敲了好几个字

楼主的条件1很模糊....写错了...我们假设是  the distance between m and 0 is 3 times the distance between r and 0

 

条件 1: |m| = 3|r|

条件 2:  m+r=24

 

上述方程有两组解答: m=18 r=6; 或者 m=36 r=-12

 


作者: plmnpler    时间: 2009-6-27 08:54

QUOTE:
以下是引用xionghuixh在2009-6-26 6:57:00的发言:

r和m是数轴上的两个数,问r的大小

1 the distance between m and 0 are 3 times the distance between m and 0

2 12 is the halfway between m and r

我选了C~~答案是E~~~我想来想去觉得是C丫~~~

条件1 是是写错了呀 我暂且当做 r 到 0 的距离是 m 到0 的距离的三倍来做

情况一 m >0  r >0

           则有(1)3m=r (2) r-12=12-m  --> m=6 r=18

情况二 m < 0 r >0

          则有(1)3m=r   (2)m+12=r-12 --> m=-12 r=36

所以,r有两个取值。不唯一。故E。


作者: Redshoe08    时间: 2009-6-27 21:18

QUOTE:
以下是引用xionghuixh在2009-6-26 6:57:00的发言:

r和m是数轴上的两个数,问r的大小

1 the distance between m and 0 are 3 times the distance between m and 0

2 12 is the halfway between m and r

我选了C~~答案是E~~~我想来想去觉得是C丫~~~

 



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