问题 解答题
阅读下面的材料,并解答问题:
问题1:已知正数,有下列命题若a+b=2,则
ab
≤1
若a+b=3,则
ab
3
2
若a+b=6,则
ab
≤3

根据以上三个命题所提供的规律猜想:若a+b=9,则
ab
______,
以上规律可表示为a+b______2
ab

问题2:建造一个容积为8立方米,深2米的长方形无盖水池,池底和池壁的造价分别为每平方米120元和80元.
(1)设池长为x米,水池总造价为y(元),求y和x的函数关系式;
(2)应用“问题1”题中的规律,求水池的最低造价.
答案

问题1:根据以上三个命题所提供的规律猜想可得:

9
2
;≥.

问题2:(1)设池长为x米,水池总造价为y(元),由容积=底面积×高,得池宽为

4
x
,y=480+320x+
1280
x

(2)底面积:8÷2=4平米,

周长最短为:8米(正方形周长最短),a+b=2

ab

池壁面积:8×2=16平米,

总造价为:120×4+16×80=1760元.

填空题
阅读理解

All the wisdom of the ages and all the stories that have delighted mankind for centuries are easily and cheaply available to all of us within the covers of books. The most unfortunate people in the world are those who have never discovered how satisfying it is to read good books.

Reading is the pleasure of the mind, which means that it is a little like a sport: your eagerness and knowledge and quickness make you a good reader. Reading is fun, not because the writer is telling you something, but because it makes your mind work. Your own imagination works along with the author's or even goes beyond his. Your experience, compared with his, brings you to the same or different conclusions, and your ideas develop as you understand his.

Every book stands by itself, like a one--family house, but books in a library are like houses in a city. Although they are separate, together they all add up to something. They are connected with each other and with other cities. Books influence each other; they link the past, the present and the future and have their own generations, like families. Wherever you start reading, you connect yourself with one of the families or ideas, and in the long run, you not only find out about the world and the people in it but also you find out about yourself, too.

Reading can only be fun if you expect it to be. If you concentrate on books somebody tells you "you ought" to read, you probably won't have fun. But if you put down a book you don’t like and try another till you find one that means something to you, and then relax yourself with it, you will almost certainly have a good time  and if you become, as a result of reading, better, wiser, kinder, or more gentle, you won't have suffered during the process.

72. In the writer's opinion, in fact reading is a process of ________.

A. listening to the author                                   B. accepting the author's ideas

C. communicating with the author and yourself             D. judging the author's work

73. The writer thinks that the most unfortunate people are those _______.

A. who don't have any books                                  B. who can't enjoy reading books

C. who don’t like books                                     D. who read too many books

74. To find pleasure in reading, you should read the books _______.

A. written by famous writers                                             B. written in humor style

C. which you like to read                                     D. which are recommended by your friends

75. The author's purpose in writing the passage is to _______.

A. show the importance of reading                               B. tell us how to make reading more effective

C. tell us how to read                              D. show the pleasure of reading

72-75 CBCD