标题: 真心求助og DS133 [打印本页] 作者: shiningsmile 时间: 2012-2-29 15:33 标题: 真心求助og DS133 133. Are all of the numbers in a certain list of 15 numbers equal? (1) The sum of all the numbers in the list is 60. (2) The sum of any 3 numbers in the list is 12. 答案选B，可是og上的解释看不太懂，有简单一点的证明方法吗？先谢过各位！作者: linchaoyi 时间: 2012-2-29 19:06
条件（2）a1+a2+a3=a2+a3+a4，所以a1=a4，多算几次就有a1=a2=a3=a4=...=a15 所以，选B作者: shiningsmile 时间: 2012-2-29 20:31
thank you