问题
单项选择题
36 If x is an integer and y=4x+3, which of the following cannot be a divisor of y ？（）
A. 5
B. 6
C. 7
D. 9
E. 23
答案
参考答案：B
解析：
The most direct way to answer this question is to realize that for any integer x, 4x+3 cannot be an even number, so it therefore cannot be divisible by even numbers. Since 6 is the only even number among the answers, it has to be the answer. The other way to approach this is to plug a series of integers, starting with 1, into the equation and eliminate the choices until only 6 is left.