单选题
If x and y are integers such that x
3 = y
2, which of the following could not be the value of y?
- (A) -1
- (B) 1
- (C) 8
- (D) 16
- (E) 27
【正确答案】
D
【答案解析】Test each choice until you find the correct answer. Could y = -1 ? Is there an integer x such that x3 = (-1)2 = 1? Yes, x = 1. Similarly, if y = 1, x = 1. Could y = 8? Is there an integer x such that x3 = (8)2 = 64? Yes, x=4. Could y = 16? Is there an integer x such that x3 = 162 = 256? No, 63 = 216, which is too small; and 73 = 343, which is too big. The answer is D.