求助PREP上的DS题

wangliming

A certain list of several different integers. Is the product of all the integers in the list positive?

1 the product of the greatest and the smallest of the integers in the list is positive

2 there is an even number of integers in the list

请问大家选什么。。。答案是c 我选的E 我的思路是:如果这组数就-4 -2 -1 三个数的话，满足12两个条件，但是就不行，若果1 2  4 的话， 就可以，所以我选E，不知道我的思路对不对。。。

What is the remainder when the positive integer n is divided by the positive integer k (k>1)

1 n=(k+1)^3

2 k=5

答案是A。。。求做法。。。

franker

1. even是偶数
2. n=(k+1)^3=k^3+3k^2+3k+1 被k除余1

xingzixin

条件2是说数字个数为even

不是there is an even number  in the list

而是there is an even number of integers in the list  就是注意不要搞混了哈 做math最怕弄丢一两个词，致命啊......