问题 解答题

某校初一年级学生搞联谊活动,派张明和刘毅同学去学校附近的市场买水果,已知该市场的苹果每千克6元,芦柑每千克3.6元,他们买这两种水果共20千克

小题1:如果他们一共带了96元,要全花掉,能买这两种水果各多少千克?

小题2:刘毅事先调查了要参加联谊活动的同学们对这两种水果的喜好,决定所买苹果数量不超过芦柑的数量,但不少于芦柑的三分之一,如果他们买x千克苹果,买这两种水果共花了y元,

①请求出x的取值范围;

②请写出用含x(千克)式子来表示y(元);

③请你帮他们计算一下,两种水果各买多少千克时,所花的钱最少,这时花了多少钱.

答案

小题1:解:设买苹果x千克,芦柑y千克

解得

小题2:①20-x≥x≥

解得:10≥x≥5

②   

③  因为当X越小y就越小,所以当x=5时,y有最小值=84

当买5千克苹果,15千克芦柑时花钱最小,这时共花84元

(1)根据化费的总钱数和买的总重量列出方程组解得两种水果量;

(2)所买苹果数量不超过芦柑的数量,但不少于芦柑的三分之一列出不等式组求得x的范围,利用水果总重量列出一次函数;根据一次函数图像求出最小值。

单项选择题
阅读理解

The Man of Many Secrets

Harry Houdini was one of the greatest American entertainers in the theater this century.He was a man famous for his escapes—from prison cells,from wooden boxes floating in rivers,from locked tanks full of water.He appeared in theaters all over Europe and America.Crowds came to see the great Houdini and his “magic”tricks.

0f course,his secret was not magic,or supernatural powers.It was simply strength.He had ability to move his toes as well as to move his fingers.He could move his body into almost any position he wanted.

Houdini started working in the entertainment world when he was 17,in 1891.He and his brother Theo performed card tricks in a New York club.They called themselves the Houdini brothers.When Harry married in 1894,he and his wife Bess worked together as magician and assistant,but for a long time they were not successful.Then Harty performed his first prison escape,in Chicago in 1898.Harry persuaded a detective to let him try to escape from the prison,and he invited the local newspaperman to watch.It was the publicity(名声)that came from this that started Harry Houdini’s success.

Harry had fingers trained to escape from handcuffs(手铐)and toes trained to escape from ankle chains,but his biggest secret was how he unlocked the prison doors.Every time he went into the prison cell,Bess gave him a kiss for good luck—and a small skeleton key,which is a key that fits many locks passed quickly from her mouth to his.

Harry used these prison escapes to build his fame.He arranged to escape from the local jail of every town he visited.In the afternoon the people of the town would read about it in their local newspapers.and in the evening every seat in the local theater would be full.What was the result? Worldwide fame,and a name remembered today.

小题1:According to the passage,Houdini’s success in prison escapes depends on   

A.his magic tricks and inhuman powers

B.his special tricks and a skeleton key

C.his unusual ability and skeleton key

D.his inhuman talents and magic tricks小题2:According to the passage,how did Houdini get the key which helped him unlock prison door?

A.He took the key from his wife’s mouth.

B.His wife passed it to his hand while kissing him.

C.His wife gave it to him by a magic trick.

D.He got it in his mouth through a kiss by his wife.小题3:It can be inferred from the passage that Houdini became famous   

A.when he was about 24

B.when he was about 17

C.after the year 1894

D.before the year 1898