题目内容
【题目】某企业准备投入适当的广告费对产品进行促销，在一年内预计销售
（万件）与广告费
（万元）之间的函数关系为
.已知生产此产品的年固定投入为3万元，每生产1万元此产品仍需再投入32万元，若每件销售价为“平均每件生产成本的150%”与“年平均每件所占广告费的50%”之和.
（1）试将年利润
（万元）表示为年广告费（万元）的函数；
（2）当年广告费投入多少万元时，企业年利润最大？最大利润为多少？
【答案】（1）
；（2）当年广告费为
万元时，企业利润最大，最大值为
万元．
【解析】
试题分析：（1）由题意可得，产品的生产成本为
万元，得到每万件销售价，进而得到年销售输入，即求解年利润的表达式；（2）令
，则
，利用基本不等式求解最值，即可得到结论.
试题解析：（1）由题意可得，产品的生产成本为万元，每万件销售价为
， （2分）
∴年销售收入为
， （4分）
∴年利润
. （6分）
（2）令，则
. （8分）
∵
,∴
,即
， （10分）
当且仅当
，即
时，
有最大值42，此时
.
即当年广告费为7万元时，企业利润最大，最大值为42万元. （12分）
【题目】阅读下面短文， 按要求补全表格。
Do you need useful and interesting books? Here we have got some for you.
Best learners
This book can give you the answers to the questions most often asked by parents, teachers and students themselves. Read this book and learn:
What the three difficulties in study are and what to do with them.
What to do if you don’t take an interest in a subject you are studying.
Twenty-six simple exercises to help you study easily and fast.
You will get more from this book. For younger students, you can buy Learn to Study for Beginners. It is easier to understand.
How to keep pets
A pet can be our best friend. Do you have pets in your house? Are they in good shape? This book not only offers you many colorful pictures of lovely pets, but also provides you with the knowledge about:
How to choose right pets for yourself.
How to build houses or nests for your pets.
How to feed the pets and how to keep them clean.
Buy this book and you will learn more.
We have many other books on sale. For more information enter www. knowbetter. com. If you buy two or more books at a time, you will get 10% off.
Best learners | What’re the three difficulties in study and how to 【1】 ________ with them. |
What if you aren’t 【2】 ________in a subject you are studying. | |
If you finish the 26 simple exercises , you can study easily and fast. | |
How to keep pets | You should choose the pets you like. |
You’d better build houses or nests for them. | |
In order to make your pets 【3】 ________, you should feed them and keep them clean. | |
The book , 【4】 ________, is better for younger students to read. | |
If you (60) ________ more information, you can go to our website. | |
