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请问以下这几道GWD是答案错了吗?

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楼主
发表于 2007-12-19 20:06:00 | 只看该作者

请问以下这几道GWD是答案错了吗?

RT

Q17:

In the figure, points A, B, C, D, and E lie on a line.  A is on both circles, B is the center

of the smaller circle, C is the center of the larger circle, D is on the smaller circle, and E

is on the larger circle.  What is the area of the region inside the larger circle and outside

the smaller circle?

(1)   AB = 3 and BC =2

(2)   CD =1 and DE = 4

(不看图也可以,我太笨,不会作图,呵呵)答案选A,我选D,因为可以求出CE=5,即大圆半径,再乘24即小圆直径。

 

 

 

 

Q32:

If xyz 0, is x (y + z) = 0?

(1)  |y + z| = |y| + |z|

(2)  |x + y| = |x| + |y|

答案选C,我选A, 因为A即可否定yz两者互为倒数的可能。

 

 

 

 

Q35:

Stations X and Y are connected by two separate, straight, parallel rail lines that are 250

miles long.  Train P and train Q simultaneously left Station X and Station Y, respectively,

and each train traveled to the other’s point of departure.  The two trains passed each other

after traveling for 2 hours.  When the two trains passed, which train was nearer to its

destination?

(1)  At the time when the two trains passed, train P had averaged a speed of 70 miles

per hour.

(2)          Train Q averaged a speed of 55 miles per hour for the entire trip.

答案选C,我选A,因为可求出在相遇时P已经走了140miles,大于全程一半。

 

 

请各位帮忙,非常感谢!


[此贴子已经被作者于2007-12-19 20:56:56编辑过]
沙发
发表于 2007-12-19 20:38:00 | 只看该作者

第一题:

两个条件分别能独立得出解,大圆半径5,小圆半径3。

=============

第二题:

条件一,得出y*z>0,即y,z同号,那么肯定单独推不出x(y+z)=0

条件二,得出x*y>0,即x,y同号,x(y+z)是不是等于零,不一定。

两个条件综合一下,就是x*y^2*z>0,即xz>0,既然xy>0,xz>0,那么x(y+z)>0

不知道答案C是什么选项?

===============

第三题:

如果都是匀速,两个条件是一样的,就是P走了140公里的地方。应该是P离终点更近。

板凳
 楼主| 发表于 2007-12-19 20:55:00 | 只看该作者

嘻嘻,谢谢LS热心,原来是我的GWD印刷有问题,第二道是问是否不小于0~

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