不懂啊，求解！！大牛快现身啊

非欧2011

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 ?

非欧2011

prep上的题，我不太懂是神吗意思，求大牛指导

800

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 ?

-- by 会员 非欧2011 (2011/10/15 1:22:15)

没见过此题，个人愚见：
the number of variations in sign(正负符号变化的次数）=相邻两个数相乘为负数有多少组
三组：（1，-3）， （-3，2），（5，-4）
所以答案应该是3
ps. the number of variations in sign 这个不重用，不理解没关系，设the number of variations in sign=X就好了，反正问题也是问X
题目就变成X=多少组相邻两个数相乘为负数
求拍！

may24

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 ?

-- by 会员 非欧2011 (2011/10/15 1:22:15)

没见过此题，个人愚见：
the number of variations in sign(正负符号变化的次数）=相邻两个数相乘为负数有多少组
三组：（1，-3）， （-3，2），（5，-4）
所以答案应该是3
ps. the number of variations in sign 这个不重用，不理解没关系，设the number of variations in sign=X就好了，反正问题也是问X
题目就变成X=多少组相邻两个数相乘为负数
求拍！

-- by 会员 800 (2011/10/15 2:24:25)

我做过这道题，同意你的观点，答案是三

lyx302

同意，得3.

Daisy_Chen

3
就是数列里面相邻的两个数字符号不同的对数。。。定义成前后2个数字相乘机位负数的对数