反比例函数图像与性质.pdf
湘教版九年级上册数学教案1.2反比例函数的图像与性质（1）教学目标1体会并了解反比例函数的图象的意义2能描点画出反比例函数的图象3结合图象分析并掌握当k0 时反比例函数的性质重点难点重点：反比例函数的图像及当k0 时反比例函数的性质难点：绘制反比例函数的图像教学设计一、预习导学自主预习教材P5-7，并思考下列问题：1画反比例函数图像的步骤是、.2反比例函数y=kx（k 为常数，k0）的图象是，当 K0 时，双曲线的两支分别位于第、象限，它们与轴、轴都不相交，在每个象限内，y 随 x 的增大而 .3函数xy20的图象在第象限,在每一象限内，y 随 x 的增大而 .二、探究展示（一）合作探究如何画反比例函数xy6的图象？由组长带领本组组员共同探讨完成。由于反比例函数y=x6的图象是曲线型的，且分成两支对此，学生第一次接触有一定的难度，因此需要分几个层次来探求：(1)可以先估计例如：位置(图象所在象限、图象与坐标轴的交点等)、趋势(上升、下降等)；(2)方法与步骤利用描点作图；列表：取自变量x 的哪些值?x 是不为零的任何实数，所以不能取x 的值的为零，但仍可以以零为基准，左右均匀，对称地取值。X-6-5-4-3-2-1.5-1 1 1.5 2 3 4 5 6 xy6-1-1.2-1.5-2-3-4-6 6 4 3 2 1.5 1.2 1 描点：依据什么(数据、方法)找点?在平面直角坐标系内，以自变量 x 的取值为横坐标，以相应的函数值y 为纵坐标，描出相应的点。连线：怎样连线?可在各个象限内按照自变量从小到大的顺序用两条光滑的曲线把所描的点连接起来。yx6-665-6-5-51-2-2-1-15-4-4-3-343243201观察上图，图像位于哪些象限？图像与坐标轴相交吗？在每一象限内，函数值y 随自变量x的变化如何变化？（点名回答）设计意图：学习正确的作图过程，在填表过程中感受y 随 x 的变化规律，为基于图象探究函数性质打下基础.（二）展示提升1完成 P6做一做，画出反比例函数xy3的图像xy6文档编码:CF5N8P4X6V7 HF9I6B4X2S2 ZF7R8V10I1V1文档编码:CF5N8P4X6V7 HF9I6B4X2S2 ZF7R8V10I1V1文档编码:CF5N8P4X6V7 HF9I6B4X2S2 ZF7R8V10I1V1文档编码:CF5N8P4X6V7 HF9I6B4X2S2 ZF7R8V10I1V1文档编码:CF5N8P4X6V7 HF9I6B4X2S2 ZF7R8V10I1V1文档编码:CF5N8P4X6V7 HF9I6B4X2S2 ZF7R8V10I1V1文档编码:CF5N8P4X6V7 HF9I6B4X2S2 ZF7R8V10I1V1文档编码:CF5N8P4X6V7 HF9I6B4X2S2 ZF7R8V10I1V1文档编码:CF5N8P4X6V7 HF9I6B4X2S2 ZF7R8V10I1V1文档编码:CF5N8P4X6V7 HF9I6B4X2S2 ZF7R8V10I1V1文档编码:CF5N8P4X6V7 HF9I6B4X2S2 ZF7R8V10I1V1文档编码:CF5N8P4X6V7 HF9I6B4X2S2 ZF7R8V10I1V1文档编码:CF5N8P4X6V7 HF9I6B4X2S2 ZF7R8V10I1V1文档编码:CF5N8P4X6V7 HF9I6B4X2S2 ZF7R8V10I1V1文档编码:CF5N8P4X6V7 HF9I6B4X2S2 ZF7R8V10I1V1文档编码:CF5N8P4X6V7 HF9I6B4X2S2 ZF7R8V10I1V1文档编码:CF5N8P4X6V7 HF9I6B4X2S2 ZF7R8V10I1V1文档编码:CF5N8P4X6V7 HF9I6B4X2S2 ZF7R8V10I1V1文档编码:CF5N8P4X6V7 HF9I6B4X2S2 ZF7R8V10I1V1文档编码:CF5N8P4X6V7 HF9I6B4X2S2 ZF7R8V10I1V1文档编码:CF5N8P4X6V7 HF9I6B4X2S2 ZF7R8V10I1V1文档编码:CF5N8P4X6V7 HF9I6B4X2S2 ZF7R8V10I1V1文档编码:CF5N8P4X6V7 HF9I6B4X2S2 ZF7R8V10I1V1文档编码:CF5N8P4X6V7 HF9I6B4X2S2 ZF7R8V10I1V1文档编码:CF5N8P4X6V7 HF9I6B4X2S2 ZF7R8V10I1V1文档编码:CF5N8P4X6V7 HF9I6B4X2S2 ZF7R8V10I1V1文档编码:CF5N8P4X6V7 HF9I6B4X2S2 ZF7R8V10I1V1文档编码:CF5N8P4X6V7 HF9I6B4X2S2 ZF7R8V10I1V1文档编码:CF5N8P4X6V7 HF9I6B4X2S2 ZF7R8V10I1V1文档编码:CF5N8P4X6V7 HF9I6B4X2S2 ZF7R8V10I1V1文档编码:CF5N8P4X6V7 HF9I6B4X2S2 ZF7R8V10I1V1文档编码:CF5N8P4X6V7 HF9I6B4X2S2 ZF7R8V10I1V1文档编码:CF5N8P4X6V7 HF9I6B4X2S2 ZF7R8V10I1V1文档编码:CF5N8P4X6V7 HF9I6B4X2S2 ZF7R8V10I1V1文档编码:CF5N8P4X6V7 HF9I6B4X2S2 ZF7R8V10I1V1文档编码:CF5N8P4X6V7 HF9I6B4X2S2 ZF7R8V10I1V1文档编码:CF5N8P4X6V7 HF9I6B4X2S2 ZF7R8V10I1V1文档编码:CF5N8P4X6V7 HF9I6B4X2S2 ZF7R8V10I1V1文档编码:CF5N8P4X6V7 HF9I6B4X2S2 ZF7R8V10I1V1文档编码:CF5N8P4X6V7 HF9I6B4X2S2 ZF7R8V10I1V1文档编码:CF5N8P4X6V7 HF9I6B4X2S2 ZF7R8V10I1V1文档编码:CF5N8P4X6V7 HF9I6B4X2S2 ZF7R8V10I1V1文档编码:CF5N8P4X6V7 HF9I6B4X2S2 ZF7R8V10I1V1文档编码:CF5N8P4X6V7 HF9I6B4X2S2 ZF7R8V10I1V1文档编码:CF5N8P4X6V7 HF9I6B4X2S2 ZF7R8V10I1V1文档编码:CF5N8P4X6V7 HF9I6B4X2S2 ZF7R8V10I1V1文档编码:CF5N8P4X6V7 HF9I6B4X2S2 ZF7R8V10I1V1文档编码:CF5N8P4X6V7 HF9I6B4X2S2 ZF7R8V10I1V1设计意图：提高学生利用描点法画反比例函数的基本技能，加深学生对反比例函数图象的认识，为下一步归纳反比例函数的性质做准备.2观察画出的xy6，xy3的图像，思考下列问题：（1）每个函数的图像分别位于哪些象限？（2）在每一象限内，函数值y 随自变量x 的变化如何变化？先由小组讨论交流，教师准确引导，及时点拨和追问，总结出规律：一般的，当K0 时，反比例函数y=kx的图像由分别在第一、第三象限内的两支曲线组成，它们与 x 轴、y 轴都不相交，在每个象限内，函数值y 随自变量 x 的增大而减小。设计意图：让学生独立思考、讨论交流，经历从特殊到一般的归纳过程，积累基本活动经验.三.知识梳理启发学生谈谈本节课的收获.1.用描点法作反比例函数图象的步骤：列表、描点、连线。2.图像性质：反比例函数y=kx（k 为常数，k0）的图象是双曲线，当K0 时，双曲线的两支分别位于第一、三象限，它们与x 轴、y 轴都不相交，在每个象限内，y 随 x 的增大而减小。四.当堂检测1画出反比例函数xy4的图像2如右图，这是下列四个函数中哪一个函数的图象（）A xy5 B 32xy C xy4 D xy33函数20yx的图象在第_ 象限,在每一象限内，y 随 x 的增大而_.4在反比例函数yxk3图象的每一支曲线上，y 都随 x 的增大而减小，则k 的取值范文档编码:CF5N8P4X6V7 HF9I6B4X2S2 ZF7R8V10I1V1文档编码:CF5N8P4X6V7 HF9I6B4X2S2 ZF7R8V10I1V1文档编码:CF5N8P4X6V7 HF9I6B4X2S2 ZF7R8V10I1V1文档编码:CF5N8P4X6V7 HF9I6B4X2S2 ZF7R8V10I1V1文档编码:CF5N8P4X6V7 HF9I6B4X2S2 ZF7R8V10I1V1文档编码:CF5N8P4X6V7 HF9I6B4X2S2 ZF7R8V10I1V1文档编码:CF5N8P4X6V7 HF9I6B4X2S2 ZF7R8V10I1V1文档编码:CF5N8P4X6V7 HF9I6B4X2S2 ZF7R8V10I1V1文档编码:CF5N8P4X6V7 HF9I6B4X2S2 ZF7R8V10I1V1文档编码:CF5N8P4X6V7 HF9I6B4X2S2 ZF7R8V10I1V1文档编码:CF5N8P4X6V7 HF9I6B4X2S2 ZF7R8V10I1V1文档编码:CF5N8P4X6V7 HF9I6B4X2S2 ZF7R8V10I1V1文档编码:CF5N8P4X6V7 HF9I6B4X2S2 ZF7R8V10I1V1文档编码:CF5N8P4X6V7 HF9I6B4X2S2 ZF7R8V10I1V1文档编码:CF5N8P4X6V7 HF9I6B4X2S2 ZF7R8V10I1V1文档编码:CF5N8P4X6V7 HF9I6B4X2S2 ZF7R8V10I1V1文档编码:CF5N8P4X6V7 HF9I6B4X2S2 ZF7R8V10I1V1文档编码:CF5N8P4X6V7 HF9I6B4X2S2 ZF7R8V10I1V1文档编码:CF5N8P4X6V7 HF9I6B4X2S2 ZF7R8V10I1V1文档编码:CF5N8P4X6V7 HF9I6B4X2S2 ZF7R8V10I1V1文档编码:CF5N8P4X6V7 HF9I6B4X2S2 ZF7R8V10I1V1文档编码:CF5N8P4X6V7 HF9I6B4X2S2 ZF7R8V10I1V1文档编码:CF5N8P4X6V7 HF9I6B4X2S2 ZF7R8V10I1V1文档编码:CF5N8P4X6V7 HF9I6B4X2S2 ZF7R8V10I1V1文档编码:CF5N8P4X6V7 HF9I6B4X2S2 ZF7R8V10I1V1文档编码:CF5N8P4X6V7 HF9I6B4X2S2 ZF7R8V10I1V1文档编码:CF5N8P4X6V7 HF9I6B4X2S2 ZF7R8V10I1V1文档编码:CF5N8P4X6V7 HF9I6B4X2S2 ZF7R8V10I1V1文档编码:CF5N8P4X6V7 HF9I6B4X2S2 ZF7R8V10I1V1文档编码:CF5N8P4X6V7 HF9I6B4X2S2 ZF7R8V10I1V1文档编码:CF5N8P4X6V7 HF9I6B4X2S2 ZF7R8V10I1V1文档编码:CF5N8P4X6V7 HF9I6B4X2S2 ZF7R8V10I1V1文档编码:CF5N8P4X6V7 HF9I6B4X2S2 ZF7R8V10I1V1文档编码:CF5N8P4X6V7 HF9I6B4X2S2 ZF7R8V10I1V1文档编码:CF5N8P4X6V7 HF9I6B4X2S2 ZF7R8V10I1V1文档编码:CF5N8P4X6V7 HF9I6B4X2S2 ZF7R8V10I1V1文档编码:CF5N8P4X6V7 HF9I6B4X2S2 ZF7R8V10I1V1文档编码:CF5N8P4X6V7 HF9I6B4X2S2 ZF7R8V10I1V1文档编码:CF5N8P4X6V7 HF9I6B4X2S2 ZF7R8V10I1V1文档编码:CF5N8P4X6V7 HF9I6B4X2S2 ZF7R8V10I1V1文档编码:CF5N8P4X6V7 HF9I6B4X2S2 ZF7R8V10I1V1文档编码:CF5N8P4X6V7 HF9I6B4X2S2 ZF7R8V10I1V1文档编码:CF5N8P4X6V7 HF9I6B4X2S2 ZF7R8V10I1V1文档编码:CF5N8P4X6V7 HF9I6B4X2S2 ZF7R8V10I1V1文档编码:CF5N8P4X6V7 HF9I6B4X2S2 ZF7R8V10I1V1文档编码:CF5N8P4X6V7 HF9I6B4X2S2 ZF7R8V10I1V1文档编码:CF5N8P4X6V7 HF9I6B4X2S2 ZF7R8V10I1V1文档编码:CF5N8P4X6V7 HF9I6B4X2S2 ZF7R8V10I1V1围是 _.若关于x,y的函数xky1图象位于第一、三象限，则k 的取值范围是_.五.教学反思本节课通过用描点法画反比例函数的图像让学生理解当k0 时反比例函数y=kx的图像性质，更直观、有效运用各种启发、激励的语言，以及小组合作交流、竞争的方式，更能激起学生的求知的欲望.学生通过展示锻炼了口头表达能力，同时培养了学生分析问题和解决问题的能力,增强了小组的凝聚力.文档编码:CF5N8P4X6V7 HF9I6B4X2S2 ZF7R8V10I1V1文档编码:CF5N8P4X6V7 HF9I6B4X2S2 ZF7R8V10I1V1文档编码:CF5N8P4X6V7 HF9I6B4X2S2 ZF7R8V10I1V1文档编码:CF5N8P4X6V7 HF9I6B4X2S2 ZF7R8V10I1V1文档编码:CF5N8P4X6V7 HF9I6B4X2S2 ZF7R8V10I1V1文档编码:CF5N8P4X6V7 HF9I6B4X2S2 ZF7R8V10I1V1文档编码:CF5N8P4X6V7 HF9I6B4X2S2 ZF7R8V10I1V1文档编码:CF5N8P4X6V7 HF9I6B4X2S2 ZF7R8V10I1V1文档编码:CF5N8P4X6V7 HF9I6B4X2S2 ZF7R8V10I1V1文档编码:CF5N8P4X6V7 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