Problem Solving
试题详情
题目：
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
选项:
A、I only
B、II only
C、III only
D、I and II
E、II and III
答案:
E
