几道prep题。。怎么也想不通！

爱玩的小新1

1.for  a finite sequenceof 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 negtive ,what is the number of variations in sign for the sequence 1 -3 2 5-4 -6?  
答案是3，题目没有看懂，，怎么也想不通。。。


2.before being simplified ,the instruction for computing income tax in country R weie add 2percent of one's annual income to the average of 100units of country R's currency and 1%of one's annual income ,which of the following represents the simplified formula for computing the income tax ,in countryR's currency,for a person in that country whose annual income is I?

这道题也是看不懂。。。求牛牛们解答。。小女子在这谢过了~~

feid1984

第一题：定义the number of variations = 多少对 序列中连续两个数（其中满足乘积是负数）   有三对：1*（-3） ；（-3）*2 ； 5*（-4）

feid1984

第二题：
income tax in country R =
2percent of one's annual income +（ the average of （100units of country R's currency and 1%of one's annual income） ）

爱玩的小新1

谢谢！~觉得第二题很绕。。看的不大明白

crjcd

第二题：
income tax in country R =
2percent of one's annual income +（ the average of （100units of country R's currency and 1%of one's annual income） ）

-- by 会员 feid1984 (2010/8/23 23:12:53)

这一解释才看得明白，哎