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《二次根式的乘法》优质课教案下载
由具体数据,发现规律,导出 EMBED Equation.DSMT4 · EMBED Equation.DSMT4 = EMBED Equation.DSMT4 (a≥0,b≥0)并运用它进行计算;利用逆向思维,得出 EMBED Equation.DSMT4 = EMBED Equation.DSMT4 · EMBED Equation.DSMT4 (a≥0,b≥0)并运用它进行解题和化简.
教学重难点关键
重点: EMBED Equation.DSMT4 · EMBED Equation.DSMT4 = EMBED Equation.DSMT4 (a≥0,b≥0), EMBED Equation.DSMT4 = EMBED Equation.DSMT4 · EMBED Equation.DSMT4 (a≥0,b≥0)及它们的运用.
难点:发现规律,导出 EMBED Equation.DSMT4 · EMBED Equation.DSMT4 = EMBED Equation.DSMT4 (a≥0,b≥0).
关键:要讲清 EMBED Equation.DSMT4 (a<0,b<0)= EMBED Equation.DSMT4 ,如 EMBED Equation.DSMT4 = EMBED Equation.DSMT4 或 EMBED Equation.DSMT4 = EMBED Equation.DSMT4 = EMBED Equation.DSMT4 × EMBED Equation.DSMT4 .
教学过程
一、复习引入
(学生活动)请同学们完成下列各题.
1.填空
(1) EMBED Equation.DSMT4 × EMBED Equation.DSMT4 =_______, EMBED Equation.DSMT4 =______;
(2) EMBED Equation.DSMT4 × EMBED Equation.DSMT4 =_______, EMBED Equation.DSMT4 =________.
(3) EMBED Equation.DSMT4 × EMBED Equation.DSMT4 =________, EMBED Equation.DSMT4 =_______.
参考上面的结果,用“>、<或=”填空.
EMBED Equation.DSMT4 × EMBED Equation.DSMT4 _____ EMBED Equation.DSMT4 , EMBED Equation.DSMT4 × EMBED Equation.DSMT4 _____ EMBED Equation.DSMT4 ,
EMBED Equation.DSMT4 × EMBED Equation.DSMT4 ________ EMBED Equation.DSMT4
2.利用计算器计算填空
(1) EMBED Equation.DSMT4 × EMBED Equation.DSMT4 ______ EMBED Equation.DSMT4 ,(2) EMBED Equation.DSMT4 × EMBED Equation.DSMT4 ______ EMBED Equation.DSMT4 ,
(3) EMBED Equation.DSMT4 × EMBED Equation.DSMT4 ______ EMBED Equation.DSMT4 ,(4) EMBED Equation.DSMT4 × EMBED Equation.DSMT4 ______ EMBED Equation.DSMT4 ,
(5) EMBED Equation.DSMT4 × EMBED Equation.DSMT4 ______ EMBED Equation.DSMT4 .
老师点评(纠正学生练习中的错误)
二、探索新知
(学生活动)让3、4个同学上台总结规律.
老师点评:(1)被开方数都是正数;
(2)两个二次根式的乘除等于一个二次根式,并且把这两个二次根式中的数相乘,作为等号另一边二次根式中的被开方数.
一般地,对二次根式的乘法规定为