which of the following can be expressed as the sum of three consecutive integers

问题描述:

which of the following can be expressed as the sum of three consecutive integers
A 17
B 23
C 25
D 30
E 40

选D,看这个数能不能被3整除
你想啊,3个连续的整数,如果第一个是x的话,后面两个不就是x+1, x+2吗?
那x+x+1+x+2=3x+3=3(x+1)