题干

某地农业监测部门统计发现:该地区近几年的生猪收购价格每四个月会重复出现,但生猪养殖成本逐月递增.下表是今年前四个月的统计情况:

月份

1月份

2月份

3月份

4月份

收购价格(元/斤)

6

7

6

5

养殖成本(元/斤)

3

4

4.6

5

现打算从以下两个函数模型:①y=Asin(ωx+φ)+B,(A>0,ω>0,﹣π<φ<π),

②y=log2(x+a)+b中选择适当的函数模型,分别来拟合今年生猪收购价格(元/斤)与相应月份之间的函数关系、养殖成本(元/斤)与相应月份之间的函数关系.

(1)请你选择适当的函数模型,分别求出这两个函数解析式;

(2)按照你选定的函数模型,帮助该部门分析一下,今年该地区生猪养殖户在接下来的月份里有没有可能亏损?

上一题 下一题 0.0难度 选择题 更新时间:2018-03-19 09:24:31

答案(点此获取答案解析)

解:(1)①选择函数模型y=Asin(ωx+φ)+B,(A>0,ω>0,﹣π<φ<π)拟合收购价格(元/斤)与相应月份之间的函数关系,

由题:A=1,B=6,T=4,∵T=2πω

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Evaluating (评价)Sources of health Information

Makinggood choices about your own health requires reasonable evaluation. A key firststep in bettering your evaluation ability is to look carefully at your sourcesof healthy information. Reasonable evaluation includes knowing where and how tofins relevant information, how to separate fact from opinions, how to recognizepoor reasoning, and how to analyze information and the reliability of sources.____ 

Goto the original source. Media reports often simplify the results of medicalresearch. Find out for yourself what a study really reported, and determinewhether it was based on good science. Think about the type of study.____

Watchfor misleading language. Some studies will find that a behavior “contributesto” or is “associated with” an outcome; this does not mean that a certaincourse must lead to a certain result.____ Carefully read or listen toinformation in order to fully understand it.

Useyour common sense. If a report seems too good to be true, probably it is. Beespecially careful of information contained in advertisements.____ Evaluate “scientific” statements carefully,and be aware of quackery(江湖骗术).____ Friends and family members can be a greatsource of ideas and inspiration, but each of us needs to find a healthylifestyle that works for us.

Developingthe ability to evaluate reasonably and independently about the health problemswill serve you well throughout your life.

A.The goal of an ad is to sell yousomething.

B.Make choices that are right for you.

C.And examine the findings of theoriginal research.

D.Be sure to work through the criticalquestions.

E.Distinguish between research reportsand public health advice.

F.The following suggestions can help yousort through the health information you receive from common sources.

G.Be aware that information may also beincorrectly explained by an author's point of view.