请问以下这几道GWD是答案错了吗？

chonheinrich

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2减4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]

michaelwzg

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。

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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？

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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。

chonheinrich

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~