TT-9-10 没人问过

Q10:

What is the value of (x - y)⁴?

(1)
                  The product of x and y is 7.

(2)
                  x and y are integers.

A. Statement (1) ALONE is sufficient, but statement (2) alone is not sufficient.

B. Statement (2) ALONE is sufficient, but statement (1) alone is not sufficient.

C. BOTH statements TOGETHER are sufficient, but NEITHER statement ALONE is sufficient.

D. EACH statement ALONE is sufficient.

E. Statements (1) and (2) TOGETHER are NOT sufficient.

答案是C，我觉得不对，因为整数有正负之分，所以可能的出X-Y=6，或8

所以应该选E

大家帮我证明一下

答案是C

xy=7和整数推出一个是1，7或者是-1，-7

不管怎样都是一样的

谢谢，明白了