问题 解答题

某商店以每件30元的价格购进一种衣服,试销中发现,这种衣服每天的销售量m(件)与每件的销售价x(元)满足一次函数m=210-3x.

(1)写出商店卖这种衣服每天的利润y(元)与每件的销售价x(元)之间的函数关系式(不考虑房租、人工等因素);

(2)如果商场要每天获得最大利润,每件衣服的售价应定为多少?并求出这最大利润.

答案

(1)∵每件商品的利润为(x-30),

∴y=(x-30)(210-3x)=-3x2+300x-6300;

(2)当x=-

300
2×(-3)
=50时,

y最大=

4•(-3)•(-6300)-3002
4×(-3)
=1200.

答:当每件衣服定为50元时,每天有最大利润,最大利润是1200元.

阅读理解

This course is for those who want to learn to type, as well as those who want to improve their typing. The course is not common. You are tested in the first class, and begin practising at one of eight different skill levels. This allows you to learn at your own speed. Each program lasts 20 hours. Bring your own paper.

Course fee: $125      Materials:  $25

Two hours for each evening for two weeks. New classes begin every two weeks.

This course is taught by a number of professional business education teachers who have successfully taught typing course before.

UNDERSTANDING COMPUTERS

This twelve-hour course is for people who do not know very much about computers, but who need to learn about them. You will learn what computers are, what they can or can’t do and how to use them.

Course fee:$75  Jan 4,7,11,14,18  Wed.&Sat. 9:00---11:30 a.m.  Equipment fee:$10

David is a professor of Computer Science at Beijing University. He has over twenty years of experience in the computer field.  

STOP SMOKING

Do you want to stop smoking? Have you ever tried and failed? Now is the time to stop smoking using the latest methods. You can stop smoking, and this twelve-course will help you do it.

Course fee:$30  Jan 2,9,16,23   Mon 2:00---5:00 p.m.

Dr. John is a practicing psychologist who has helped hundreds of people stop smoking.

小题1:If you choose the UNDERSTANDING COMPUTERS course, you will have

classes_______.

A.twice

B.three times

C.four times

D.five times小题2:Mr. Black works every morning and evening, but he wants to take part in one of the three

courses. Your suggestion is __________.

A.TYPING

B.UNDERSTANDING COMPUTERS

C.STOP SMOKING

D.all the courses小题3:If you want to learn about computers, and at the same time you want to improve your

typing, you will pay  ______________.

A.$75

B.$150

C.$115

D.$235小题4:The special difference between the TYPING course and the other two is that __________.

A.people with different skill levels pay differently.

B.you will take a test in the first class for level decision

C.you will pay the fee before practicing typing.

D.you will pay less money for your study.

问答题 简答题