这道prep1的数学题怎么也看不懂题。。。

Carrie2009

For a finite sequence of nonzero numbers, the number of variations in sign is defined as the number of pairs of consecutive terms of the sequence for which the product of the two consecutive terms is negative. What is the number of variations in sign for the sequence 1, -3, 2, 5, -4, -6 ?

答案是Three.  完全不知道它在说什么。。。

amyyan

就是说number of variations in sign 的定义是：有几个相邻的两个数的乘积是负数
所以这组数的number of variations in sign有三个：因为只有1*-3， -3*2， 5*-4 ， 这三组是负数

Carrie2009

终于明白了，谢谢！