GWD-2-gmat-8
Q8:
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
LACE w:st="on">E. IILACE> and III
Answer: E
请教，这道题怎么做呀？谢谢。 | 
