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1、一元二次方程应用题教案3乐学教育-您值得信赖的专业化个性化辅导学校 乐学教育个性化辅导授课案ggggggggggggangganggang纲 教师:杜萍 学生: 时间: 2012年 月 日 段 一、授课目的与考点分析: 列一元一次方程解应用题的几种常见题型及其特点 二、授课内容: 列一元一次方程解应用题的几种常见题型及其特点 列一元一次方程解应用题是七年级数学教学中的一大重点，而列一元一次方程解应用题又是学生从小学升入中学后第一次接触到用代数的方法处理应用题。因此 ，认真学好这一知识，对于今后学习整个中学阶段的列方程(组)解应用题大有帮助。因此将列一元一次方程解应用题的几种常见题型及其特点归纳
2、下来，如下: (1)行程问题。 要掌握行程中的基本关系:路程,速度时间。 相遇问题(相向而行)，这类问题的相等关系是:各人走路之和等于总路程或同时走时两人所走的时间相等为等量关系。 追及问题(同向而行?同地不同时出发?同时不同地出发)，这类问题的等量关系是:两人的路程差等于追及的路程或以追及时间为等量关系。 环形跑道上的相遇和追及问题:同地反向而行的等量关系是两人走的路程和等于一圈的路程;同地同向而行的等量关系是两人所走的路程差等于一圈的路程。 航行问题:速度关系是: ?顺水速度,静水中速度，水流速度;?逆水速度,静水中速度,水流速度。 飞行问题、基本等量关系: ?顺风速度,无风速度，风速 ?
3、逆风速度,无风速度,风速 桥上(离桥)问题:?车上桥:车头接触到桥到车尾接触到桥的一段过程。路程为一个车长。 ?车离桥:车头离开桥到车尾离开桥的一段过程。路程为一个车长。 ?车过桥:车头接触到桥到车尾离开桥。路程为车长加桥长。 ?车在桥上:车尾接触到桥到车头离开桥。路程为桥长减车长。 行程问题可以采用画示意图的辅助手段来帮助理解题意，并注意两者运动时出发的时间和地点。 (2)和、差、倍、分问题。 此问题中常用“多、少、大、小、几分之几”或“增加、减少、缩小”等等词语体现等量关系。审题时要抓住关键词，确定标准量与比校量，并注意每个词的细乐学教育-您值得信赖的专业化个性化辅导学校 微差别。类似于:
4、甲乙两数之和56，甲比乙多3(乙是甲的1/3)，求甲乙各多少,这样的问题就是和倍问题。问题的特点是，已知两个量之间存在和倍差关系，可以求这两个量的多少。基本方法是:以和倍差中的一种关系设未知数并表示其他量，选用余下的关系列出方程。 (3)等积变形问题。 此类问题的关键在“等积”上，是等量关系的所在，必须掌握常见几何图形的面积、体积公式。 (4)工程问题。 其基本数量关系:工作总量,工作效率工作时间;合做的效率,各单独做的效率的和。当工作总量未给出具体数量时，常设总工作量为“1”，分析时可采用列表或画图来帮助理解题意。 商品利润(5)利润率问题。 其数量关系是:商品的利润率，商品利润,商品售价,
5、商品,商品进价进价。注意打几折销售就是按原价的十分之几出售。 知能点1:行程问题 基本量之间的关系: 路程,速度时间 时间,路程?速度 速度,路程?时间 (1)相遇问题 (2)追及问题 快行距，慢行距,原距 快行距,慢行距,原距 (3)航行问题 顺水(风)速度,静水(风)速度，水流(风)速度 逆水(风)速度,静水(风)速度,水流(风)速度 抓住两码头间距离不变，水流速和船速(静不速)不变的特点考虑相等关系( 1. 甲、乙两站相距480公里，一列慢车从甲站开出，每小时行90公里，一列快车从乙站开出，每小时行140公里。 (1)慢车先开出1小时，快车再开。两车相向而行。问快车开出多少小时后两车相遇
6、, (2)两车同时开出，相背而行多少小时后两车相距600公里, (3)两车同时开出，慢车在快车后面同向而行，多少小时后快车与慢车相距600公里, (4)两车同时开出同向而行，快车在慢车的后面，多少小时后快车追上慢车, (5)慢车开出1小时后两车同向而行，快车在慢车后面，快车开出后多少小时追上慢车, 此题关键是要理解清楚相向、相背、同向等的含义，弄清行驶过程。故可结合图形分析。 乐学教育-您值得信赖的专业化个性化辅导学校 2. 甲乙两人在同一道路上从相距5千米的A、B两地同向而行，甲的速度为5千米/小时，乙的速度为3千米/小时，甲带着一只狗，当甲追乙时，狗先追上乙，再返回遇上甲，再返回追上乙，依
7、次反复，直至甲追上乙为止，已知狗的速度为15千米/小时，求此过程中，狗跑的总路程是多少, 3. 某船从A地顺流而下到达B地，然后逆流返回，到达A、B两地之间的C地，一共航行了7小时，已知此船在静水中的速度为8千米/时，水流速度为2千米/时。A、C两地之间的路程为10千米，求A、B两地之间的路程。 4. 有一火车以每分钟600米的速度要过完第一、第二两座铁桥，过第二铁桥比过第一铁桥需多5秒，又知第二铁桥的长度比第一铁桥长度的2倍短50米，试求各铁桥的长( 5(已知甲、乙两地相距120千米，乙的速度比甲每小时快1千米，甲先从A地出发2小时后，乙从B地出发，与甲相向而行经过10小时后相遇，求甲乙的速
8、度, 乐学教育-您值得信赖的专业化个性化辅导学校 6 (一队学生去军事训练，走到半路，队长有事要从队头通知到队尾，通讯员以18米/分的速度从队头至队尾又返回，已知队伍的行进速度为14米/分。问:,若已知队长320米，则通讯员几分钟返回,若已知通讯员用了25分钟，则队长为多少米, 7(一架飞机在两个城市之间飞行，风速为24千米/小时，顺风飞行需要2小时50分，逆风飞行需要3小时，求两个城市之间的飞行路程, 8(一轮船在甲、乙两码头之间航行，顺水航行需要4小时，逆水航行需要5小时，水流的速度为2千米/时，求甲、乙两码头之间的距离。 知能点2:若干应用问题等量关系的规律 (1)和、差、倍、分问题 此
9、类题既可有示运算关系，又可表示相等关系，要结合题意特别注意题目中的关键词语的含义，如相等、和差、几倍、几分之几、多、少、快、慢等，它们能指导我们正确地列出代数式或方程式。 增长量,原有量增长率 现在量,原有量，增长量 (2)等积变形问题 常见几何图形的面积、体积、周长计算公式，依据形虽变，但体积不变( 2, ?圆柱体的体积公式 V=底面积高,S?h,rh ?长方体的体积 V,长宽高,abc 9 .某粮库装粮食，第一个仓库是第二个仓库存粮的3倍，如果从第一个仓库中取出20吨放入第5二个仓库中，第二个仓库中的粮食是第一个中的。问每个仓库各有多少粮食, 7乐学教育-您值得信赖的专业化个性化辅导学校
10、10 .一个装满水的内部长、宽、高分别为300毫米，300毫米和80毫米的长方体铁盒中的水，倒入一个内径为200毫米的圆柱形水桶中，正好倒满，求圆柱形水桶的高(精确到0.1毫米，?,3.14)( 211.长方体甲的长、宽、高分别为260mm，150mm，325mm，长方体乙的底面积为130130mm，又知甲的体积是乙的体积的2.5倍，求乙的高, 知能点3:调配问题。 12. 学校组织植树活动，已知在甲处植树的有23人，在乙处植树的有17人.现调20人去支援，使在甲处植树的人数是乙处植树人数的2倍多3人，应调往甲、乙两处各多少人, 13. 某中学组织同学们春游，如果每辆车座45人，有15人没座位
11、，如果每辆车座60人，那么空出一辆车，其余车刚好座满，问有几辆车，有多少同学, 14.七年级三班学生参加义务劳动，原来每组8人，后来根据需要重新编组，每组14人，这样比原来减少3组。问这个班共有学生多少人, 乐学教育-您值得信赖的专业化个性化辅导学校 三、本次课后作业: 四、学生对于本次课的评价: ? 特别满意 ? 满意 ? 一般 ? 差 学生签字: 五、教师评定: 1、 学生上次作业评价: ? 好 ? 较好 ? 一般 ? 差 2、 学生本次上课情况评价: ? 好 ? 较好 ? 一般 ? 差 教师签字: 主任签字: _ 乐学教育教务处 乐学教育-您值得信赖的专业化个性化辅导学校 (英文版 )
12、easily blame, to prevent the broken window effect. Supervise the leading cadres to play an exemplary role, take the lead in the strict implementation of the and , lead to safeguard the solemnity and authority of the party discipline, ensure that the party discipline and the laws and regulations for
13、implementation in place. Throughout the discipline in the daily supervision and management , strengthen supervision and inspection, from the thorough investigation of violations of discipline behavior. Strengthen to key areas, key departments and key projects as well as the masses reflect the concen
14、tration of the units and departments for supervision. - strengthening supervision, discipline inspection and supervision of cadres to set an example for compliance with the and is a man must be hexyl, blacksmith needs its own hardware. Discipline inspection organs as the executor of the party discip
15、line, and supervisor of the defenders, for its supervision must be more strictly, discipline inspection and supervision of cadres to firmly establish the awareness of Party Constitution, sense of discipline and rules consciousness, politics loyalty, sense obey. Action speak Ji Ordinance to set an ex
16、ample of the regulations of the rule of law, strengthen supervision and accept the supervision of the firmness and consciousness, do comply with and . To firmly establish the discipline must first be disciplined, the supervisor will be subject to the 乐学教育-您值得信赖的专业化个性化辅导学校 supervision of concept, and
17、 consciously safeguard and implement party compasses party, take the lead in practicing three strict real strict, so loyal, clean, play. To be good at learning, the Constitution and the as morality, politics and brought to fruition; to implement , do not want to, dare not, not with disciplinary rule
18、r to supervision; to discipline a ruler, often the control inspection, and consciously in the ideological red line to draw the row Ming Good accumulation is indeed the bottom line, so that the heart has fear, said to have quit, the line has ended. Attached: indifferent to heart, calmly to the table
19、in our life, there are many unpredictable things will happen, some good, some bad things, we cannot control is powerless to stop, but with time, you will find in life sometimes turns out to be not good, some bad things finally turned out to be a good thing, but then we muddy however did not know, th
20、is is the life teach us things. 1, life can be complex, can also be simple. Want simple life of precipitation, to have enough time to reflect, to make Become more perfect. Life is the most important thing is not to win, but the struggle; not to have conquered, but to have fought well. 2, the plain i
21、s the background of life. Live a plain life, give up on themselves is not a coward, but the wise answers; not disillusioned after the heart, such as ashes, but experience the storm after the enlightenment; not unrewarding perfunctorily, but calm attitude of life of unrestrained self-confidence. Plai
22、n living, there is no noise noisy, no earthly troubles, more did not fill in the discontent of desire, 乐学教育-您值得信赖的专业化个性化辅导学校 some just a calm, a calm. 3, memory of heart will not good things to erase the, life is a When no movie, pain is a beginning, the struggle is a kind of process, death is a kin
23、d of ending. Give up this giving up is the helpless, do not give up the abandoned, do not give up this giving up is ignorance, do not give up should not give up is persistent. 4, a thing figured is heaven, think impassability is hell. Since the living, to live better. Sometimes we because of too nar
24、row-minded, too care around the chores and penny wise and pound foolish, not worth the candle. Some things to attract trouble and worry, completely depends on how we look at and deal with it. Dont always take everything back to things, and dont get into a blind alley, dont want to face, dont be narr
25、ow-minded. Poke to care, is a kind of open-minded, a free and easy. 5, I am not afraid of others behind me a knife, I afraid to look back and see stab me, is my intention to treat people; I am not afraid of the truth to tell the best friend, Im afraid he turned to it as a joke to tell dont 6, when w
26、e are in a positive frame of mind, you will find many good things; and when we are in a negative state of mind, you will find many depressed things; life happy and worry, all is you of life attitude, optimistic, good luck; loss of sink, Eritrea company. When you are in adversity, may wish to change
27、a point of view to think everything over to the good Think, because good mentality decided the fate of the! 7, people are tired, rest; heart tired, calm. Grow up, mature, this society read. Tired and sad, squat down, to their a hug. Because the world no one can 乐学教育-您值得信赖的专业化个性化辅导学校 sympathize with
28、you, have mercy on you. You cry, tears is your own; you pain, no one can understand. Then you only tears to smile. 8, each people have youth, Each youth are a story, the life of the world never gets easier, I want what, wish the world all know, as has been the same; now want anything, for fear that
29、others know, or like to lose the same. 9, the heart move, everything in the world is followed by birth, Rangrang, important thing is often the most difficult to open ones mouth, because words will reduce its importance; to let strangers people care about your life in the good things, the original is
30、 not easy 10, do not blame, do not laugh at who, also dont envy who. Like a person is a kind of feeling, not like a person is true. The truth is easy to explain, I feel Is unspeakable. The best travel life is that you in a strange place found a long lost touched. 11, happy life not in the bustling i
31、n, and in the peace of mind; no matter how many grievances, how uncomfortable, and ultimately to heal themselves or their own, others may got you to comfort, but never know your heart is how wanjianchuanxin. 12, maam, like a movie, learn to appreciate, learn to be grateful, learn tolerance, and good
32、ness, helping others. Instead of accusing the society, as into one; and an exception is better to give than to what 13, dont envy him A sum of, dont lose your life and the life, respectively is: the former is a we experienced cannot escape in a day finally will last minute, while the latter is our p
33、ersistent, we want to cherish the memory of those people and things. 乐学教育-您值得信赖的专业化个性化辅导学校 14, learn to smile, learn to strong, the world you know so many people, so many people and you are, you cannot change also cant let everyone like you, so also do not want to do. Life is too short to go crazy t
34、o love to go to waste, to chase the dream to regret. 15, when temper, a blessing to go. A wounding elegant people, the key is to control their own emotions. With the mouth is the most stupid behavior. A control negative emotions than a can take a city more powerful water flow slow, language is expen
35、sive. People spent two years of time to learn to speak, but to spend a few years time to shut up. That is a kind of ability, that is a kind of wisdom. 16, life is not perfect, sometimes, growth is not a cry, not an eyeful of tears, there is no trace of emotion, there is no gleam of hope, no desire,
36、no action, no static, there is only one kind of downward sinking feeling, sink A murky? 6? 7? 6? 7 sink? 6? 7? 6? 7 toward the bottom of the sink. 17, in some way, do not go, you will not know the other side scenery is beautiful. To you is not good, you do not mind too much, no one has an obligation
37、 to you; you learn knowledge, is you have weapons, you can start from scratch, but not unarmed; how do you treat people, does not represent how others treat you, if cannot see through this point, only inviting worry. 18, time is like a sponge in the water, as long as you are willing to squeeze, the
38、total water is still there. Every life, after the ups and downs The best test of live, to life, survival and continuation, do not stop the struggle in the joys and sorrows of life on the road, so that different soul to bear life beat, acceptance of 乐学教育-您值得信赖的专业化个性化辅导学校 suffering. 19, indifferent to
39、 heart, calmly in table, elegant and comfortable life, do not take what is so important. The pursuit will be disappointed; to be alive, you will have trouble. Life is the most afraid of what all want to care about, but also what all grasp is not firm, without scenery, separated populations, such as
40、not to desire, all docked in the fate of the end. Why is too rigid, the natural, to go stay not to live, let go of obsession, revel is 20, if the fate of the broken Hopes of sailing, please dont despair, the coast is still, if the fate of the withered petals of the beautiful, please do not sink, the
41、 spring is still, life will always be endless trouble, please dont helpless, because they are still alive, is still a dream, the sun still, we still. Lost, keep memories; to get, must work to; but the most important is good to cherish their own. 21, life, select the complex, is to choose the pain; c
42、hoose a simple, is choose to be happy. The complex world like a Significance of pride. Hope is the ornate palace, outside people admiring the magnificent, living in the deep knowledge of living it to pay the price. Simple world as a simple log cabin outside ridiculed shabby, the heart is willing to
43、go live to know the joy. Suffering and joy is their own choice. 22, learn how to use a single powerful heart, let the past be the past, let the future come. Life is really the end of the end of an eagle is flying wings, life is constantly pursuit. Dont miss to regret, dont wait for old just miss. Ti
44、me to return, seize every moment, again painstakingly again tired also Those struggling to fly. 23, life could not Yimapingchuan, even flat 乐学教育-您值得信赖的专业化个性化辅导学校 pavement, inevitably there will be a few pieces of roadblocks. Some of the rocks around the past, while others have to move it out. Just m
45、ove others put the stone is very easy, because the stone from the appearance we can discern; difficult to myself to move away the heart of stone head. Leave time to spend with her, often reflect my heart, so as to remove your heart of stone. 24, everything does not have to be demanding, come to, eve
46、rything does not have to care about, over the past; failing to do not frown, laugh it laugh. Results Dont demand, do to; life is a simple, calm and peaceful. Always not to choose their own path and regret, life is like a train, the scenery and then the United States will retreat, the passage of time
47、 and encounter will eventually drifting further and further away, before is always himself. 25, everyone has a weakness, weakness is true humanity. That has no weakness, a shallow person. That people think there is no weakness, mostly false. Life has shortcomings, there are shortcomings is the real
48、life. That no one regret, or childish or numbness or Self deception. It is in tolerance of weakness and so on to accept, people live happily. Hello, everyone! I am a party member. The title of my speech is: study and implement the partys two laws, doing practical play highway. 2015 October 18, the Central Committee of the Communist Party of China promulgated the implementation of the and Chinese Communist Party 乐学教育-您值得信赖的专业化个性化辅导学校 discipline and punishment regulations. We Hey