反比例函数的意义.pdf
探索构建新课程理念下的课堂教学有效模式-“小组合作学习研究”之教案设计学科:数学教学内容:反比例函数的意义教师姓名:xxx 教学目标：1使学生理解并掌握反比例函数的概念2能判断一个给定的函数是否为反比例函数，并会用待定系数法求函数解析式3 能根据实际问题中的条件确定反比例函数的解析式，体会函数的模型思想教学重难点：教学重点：理解反比例函数的概念，能根据已知条件写出函数解析式教学难点：理解反比例函数的概念课前准备：课时安排教学过程一、情景导入资料助读课堂引入 1、什么叫函数？什么是一次函数？什么是正比例函数？)(1a二、自主学习小组合作分组自学，小组成员之间进行讨论，不能解决的与其他组进行讨论三、生生合作探求新知一般地，如果变量y 和x 之间函数关系可以表示成（k是常数,思考：下列问题中，变量间的对应关系可以用怎样的函数关系表示？这些函数有什么共同特点？1）、京沪铁路全程为1463km，某次列车的平均速度为v（km/h）随此次列车的全程运行时间t（h）的变化而变化2）、某住宅小区要种植一个面积为1000m2的矩形草坪，草坪的长 y(单位:m)随宽 x(单位:m)的变化而变化。3）、已知北京市的总面积为1.68104 平方千米，人均占有的土地面积 s(单位:平方千米/人)随全市总人口 n(单位:人)的变化而变化。且k0）的形式,则称y 是x 的反比例函数.思考：反比例函数中自变量x的取值范围是什么?反比例函数的等到价形式：y=kx-1 xy=k xkytv1463xy1000nsxytv41 06 8.1,1 0 0 0,1 4 6 3文档编码:CM6J9V7T4O2 HL1T5K6O4I8 ZF6C1A2W3C6文档编码:CM6J9V7T4O2 HL1T5K6O4I8 ZF6C1A2W3C6文档编码:CM6J9V7T4O2 HL1T5K6O4I8 ZF6C1A2W3C6文档编码:CM6J9V7T4O2 HL1T5K6O4I8 ZF6C1A2W3C6文档编码:CM6J9V7T4O2 HL1T5K6O4I8 ZF6C1A2W3C6文档编码:CM6J9V7T4O2 HL1T5K6O4I8 ZF6C1A2W3C6文档编码:CM6J9V7T4O2 HL1T5K6O4I8 ZF6C1A2W3C6文档编码:CM6J9V7T4O2 HL1T5K6O4I8 ZF6C1A2W3C6文档编码:CM6J9V7T4O2 HL1T5K6O4I8 ZF6C1A2W3C6文档编码:CM6J9V7T4O2 HL1T5K6O4I8 ZF6C1A2W3C6文档编码:CM6J9V7T4O2 HL1T5K6O4I8 ZF6C1A2W3C6文档编码:CM6J9V7T4O2 HL1T5K6O4I8 ZF6C1A2W3C6文档编码:CM6J9V7T4O2 HL1T5K6O4I8 ZF6C1A2W3C6文档编码:CM6J9V7T4O2 HL1T5K6O4I8 ZF6C1A2W3C6文档编码:CM6J9V7T4O2 HL1T5K6O4I8 ZF6C1A2W3C6文档编码:CM6J9V7T4O2 HL1T5K6O4I8 ZF6C1A2W3C6文档编码:CM6J9V7T4O2 HL1T5K6O4I8 ZF6C1A2W3C6文档编码:CM6J9V7T4O2 HL1T5K6O4I8 ZF6C1A2W3C6文档编码:CM6J9V7T4O2 HL1T5K6O4I8 ZF6C1A2W3C6文档编码:CM6J9V7T4O2 HL1T5K6O4I8 ZF6C1A2W3C6文档编码:CM6J9V7T4O2 HL1T5K6O4I8 ZF6C1A2W3C6文档编码:CM6J9V7T4O2 HL1T5K6O4I8 ZF6C1A2W3C6文档编码:CM6J9V7T4O2 HL1T5K6O4I8 ZF6C1A2W3C6文档编码:CM6J9V7T4O2 HL1T5K6O4I8 ZF6C1A2W3C6文档编码:CM6J9V7T4O2 HL1T5K6O4I8 ZF6C1A2W3C6文档编码:CM6J9V7T4O2 HL1T5K6O4I8 ZF6C1A2W3C6文档编码:CM6J9V7T4O2 HL1T5K6O4I8 ZF6C1A2W3C6文档编码:CM6J9V7T4O2 HL1T5K6O4I8 ZF6C1A2W3C6文档编码:CM6J9V7T4O2 HL1T5K6O4I8 ZF6C1A2W3C6文档编码:CM6J9V7T4O2 HL1T5K6O4I8 ZF6C1A2W3C6文档编码:CM6J9V7T4O2 HL1T5K6O4I8 ZF6C1A2W3C6文档编码:CM6J9V7T4O2 HL1T5K6O4I8 ZF6C1A2W3C6文档编码:CM6J9V7T4O2 HL1T5K6O4I8 ZF6C1A2W3C6文档编码:CM6J9V7T4O2 HL1T5K6O4I8 ZF6C1A2W3C6文档编码:CM6J9V7T4O2 HL1T5K6O4I8 ZF6C1A2W3C6文档编码:CM6J9V7T4O2 HL1T5K6O4I8 ZF6C1A2W3C6文档编码:CM6J9V7T4O2 HL1T5K6O4I8 ZF6C1A2W3C6文档编码:CM6J9V7T4O2 HL1T5K6O4I8 ZF6C1A2W3C6文档编码:CM6J9V7T4O2 HL1T5K6O4I8 ZF6C1A2W3C6文档编码:CM6J9V7T4O2 HL1T5K6O4I8 ZF6C1A2W3C6文档编码:CM6J9V7T4O2 HL1T5K6O4I8 ZF6C1A2W3C6文档编码:CM6J9V7T4O2 HL1T5K6O4I8 ZF6C1A2W3C6文档编码:CM6J9V7T4O2 HL1T5K6O4I8 ZF6C1A2W3C6文档编码:CM6J9V7T4O2 HL1T5K6O4I8 ZF6C1A2W3C6文档编码:CM6J9V7T4O2 HL1T5K6O4I8 ZF6C1A2W3C6文档编码:CM6J9V7T4O2 HL1T5K6O4I8 ZF6C1A2W3C6文档编码:CM6J9V7T4O2 HL1T5K6O4I8 ZF6C1A2W3C6文档编码:CM6J9V7T4O2 HL1T5K6O4I8 ZF6C1A2W3C6四、师生合作把握新知例 1 下列关系式中的 y 是 x 的反比例函数吗？如果是，比例系数 k 是多少？1）y=4/x 2)y=-1/2x 3)y=1-x 4)xy=1 5)y=x/2 练习：1、关系式 xy+4=0 中y 是 x 的反比例函数吗?若是，比例系数 k 等于多少？若不是，请说明理由2、下列函数中哪些是反比例函数?哪些是一次函数?（课件展示）例题 2、已知 y 是 x 的反比例函数,当 x=2 时,y=6.(1)写出 y 与 x 的函数关系式:(2)求当 x=4 时 y 的值.分析：因为 y 是 x 的反比例函数，所以先设xky，再把 x2 和 y6 代入上式求出常数k，即利用了待定系数法确定函数解析式。五、练习检测评价反馈课堂练习：1.y 是 x 的反比例函数,当 x=3 时,y=-6.(1)写出 y与 x 的函数关系式.(2)求当 y=4 时 x 的值.2.y 是 x-2 的反比例函数,当 x=3 时,y=4.(1)求 y 与 x 的函数关系式.(2)当 x=-2 时,求 y 的值.补充例题：已知函数yy1y2，y1 与x1 成正比例，y2 与x 成反比例，且当 x1 时，y0；当 x4 时,y 9，求当 x1 时 y 的值是多少?文档编码:CM6J9V7T4O2 HL1T5K6O4I8 ZF6C1A2W3C6文档编码:CM6J9V7T4O2 HL1T5K6O4I8 ZF6C1A2W3C6文档编码:CM6J9V7T4O2 HL1T5K6O4I8 ZF6C1A2W3C6文档编码:CM6J9V7T4O2 HL1T5K6O4I8 ZF6C1A2W3C6文档编码:CM6J9V7T4O2 HL1T5K6O4I8 ZF6C1A2W3C6文档编码:CM6J9V7T4O2 HL1T5K6O4I8 ZF6C1A2W3C6文档编码:CM6J9V7T4O2 HL1T5K6O4I8 ZF6C1A2W3C6文档编码:CM6J9V7T4O2 HL1T5K6O4I8 ZF6C1A2W3C6文档编码:CM6J9V7T4O2 HL1T5K6O4I8 ZF6C1A2W3C6文档编码:CM6J9V7T4O2 HL1T5K6O4I8 ZF6C1A2W3C6文档编码:CM6J9V7T4O2 HL1T5K6O4I8 ZF6C1A2W3C6文档编码:CM6J9V7T4O2 HL1T5K6O4I8 ZF6C1A2W3C6文档编码:CM6J9V7T4O2 HL1T5K6O4I8 ZF6C1A2W3C6文档编码:CM6J9V7T4O2 HL1T5K6O4I8 ZF6C1A2W3C6文档编码:CM6J9V7T4O2 HL1T5K6O4I8 ZF6C1A2W3C6文档编码:CM6J9V7T4O2 HL1T5K6O4I8 ZF6C1A2W3C6文档编码:CM6J9V7T4O2 HL1T5K6O4I8 ZF6C1A2W3C6文档编码:CM6J9V7T4O2 HL1T5K6O4I8 ZF6C1A2W3C6文档编码:CM6J9V7T4O2 HL1T5K6O4I8 ZF6C1A2W3C6文档编码:CM6J9V7T4O2 HL1T5K6O4I8 ZF6C1A2W3C6文档编码:CM6J9V7T4O2 HL1T5K6O4I8 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ZF6C1A2W3C6文档编码:CM6J9V7T4O2 HL1T5K6O4I8 ZF6C1A2W3C6文档编码:CM6J9V7T4O2 HL1T5K6O4I8 ZF6C1A2W3C6拓展练习。（课件展示）六、交流习得巩固新知课堂小结布置作业。文档编码:CM6J9V7T4O2 HL1T5K6O4I8 ZF6C1A2W3C6文档编码:CM6J9V7T4O2 HL1T5K6O4I8 ZF6C1A2W3C6文档编码:CM6J9V7T4O2 HL1T5K6O4I8 ZF6C1A2W3C6文档编码:CM6J9V7T4O2 HL1T5K6O4I8 ZF6C1A2W3C6文档编码:CM6J9V7T4O2 HL1T5K6O4I8 ZF6C1A2W3C6文档编码:CM6J9V7T4O2 HL1T5K6O4I8 ZF6C1A2W3C6文档编码:CM6J9V7T4O2 HL1T5K6O4I8 ZF6C1A2W3C6文档编码:CM6J9V7T4O2 HL1T5K6O4I8 ZF6C1A2W3C6文档编码:CM6J9V7T4O2 HL1T5K6O4I8 ZF6C1A2W3C6文档编码:CM6J9V7T4O2 HL1T5K6O4I8 ZF6C1A2W3C6文档编码:CM6J9V7T4O2 HL1T5K6O4I8 ZF6C1A2W3C6文档编码:CM6J9V7T4O2 HL1T5K6O4I8 ZF6C1A2W3C6文档编码:CM6J9V7T4O2 HL1T5K6O4I8 ZF6C1A2W3C6文档编码:CM6J9V7T4O2 HL1T5K6O4I8 ZF6C1A2W3C6文档编码:CM6J9V7T4O2 HL1T5K6O4I8 ZF6C1A2W3C6文档编码:CM6J9V7T4O2 HL1T5K6O4I8 ZF6C1A2W3C6文档编码:CM6J9V7T4O2 HL1T5K6O4I8 ZF6C1A2W3C6文档编码:CM6J9V7T4O2 HL1T5K6O4I8 ZF6C1A2W3C6文档编码:CM6J9V7T4O2 HL1T5K6O4I8 ZF6C1A2W3C6文档编码:CM6J9V7T4O2 HL1T5K6O4I8 ZF6C1A2W3C6文档编码:CM6J9V7T4O2 HL1T5K6O4I8 ZF6C1A2W3C6文档编码:CM6J9V7T4O2 HL1T5K6O4I8 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