GWD1.一道数学题```请教

ningxiaoye

The operation Ä is defined for all nonzero numbers a and b by a Ä b = a/b – b/a.  If x and y are nonzero numbers, which of the following statements must be true?

 

 

 

 

I.                    x Ä xy = x(1 Ä y)

II.                 x Ä y = -(y Ä x)

III.               1/x Ä 1/y = y Ä x

 

 

 

 

A.   I only

B.    II only

C.   III only

D.   I and II

E.    II and III

  Answer: E

我觉得全都对啊?汗~~~

哦，明白了，粗心了粗心了```

[此贴子已经被作者于2008-4-23 17:37:09编辑过]