2022年21.2二次根式的乘除2 .pdf
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1、名师精编优秀教案21.2 二次根式的乘除(3)第三课时教学内容最简二次根式的概念及利用最简二次根式的概念进行二次根式的化简运算教学目标理解最简二次根式的概念,并运用它把不是最简二次根式的化成最简二次根式通过计算或化简的结果来提炼出最简二次根式的概念,并根据它的特点来检验最后结果是否满足最简二次根式的要求重难点关键 1重点:最简二次根式的运用 2难点关键:会判断这个二次根式是否是最简二次根式教学过程一、复习引入(学生活动)请同学们完成下列各题(请三位同学上台板书)1计算(1)35,(2)3 227,(3)82a老师点评:35=155,3 227=63,82a=2 aa 2现在我们来看本章引言中的
2、问题:如果两个电视塔的高分别是h1km,h2km,?那么它们的传播半径的比是_它们的比是1222RhRh二、探索新知观察上面计算题1 的最后结果,可以发现这些式子中的二次根式有如下两个特点:1被开方数不含分母;2被开方数中不含能开得尽方的因数或因式我们把满足上述两个条件的二次根式,叫做最简二次根式那么上题中的比是否是最简二次根式呢?如果不是,把它们化成最简二次根式学生分组讨论,推荐34 个人到黑板上板书老师点评:不是名师精编优秀教案1222RhRh=121122222h hRhhRhhh.例 1(1)5312;(2)2442x yx y;(3)238x y例 2如图,在RtABC中,C=90,
3、AC=2.5cm,BC=6cm,求 AB的长BAC解:因为AB2=AC2+BC2 所以 AB=222.56=2516916913()362424=6.5(cm)因此 AB的长为 6.5cm三、巩固练习教材 P14练习 2、3 四、应用拓展例 3观察下列各式,通过分母有理数,把不是最简二次根式的化成最简二次根式:121=1(21)2121(21)(21)=2-1,132=1(32)3232(32)(32)=3-2,同理可得:143=4-3,从计算结果中找出规律,并利用这一规律计算(121+132+143+120022001)(2002+1)的值文档编码:CJ10C2X5I1P7 HQ3D3W7A
4、4F10 ZS7Q8O4X2J2文档编码:CJ10C2X5I1P7 HQ3D3W7A4F10 ZS7Q8O4X2J2文档编码:CJ10C2X5I1P7 HQ3D3W7A4F10 ZS7Q8O4X2J2文档编码:CJ10C2X5I1P7 HQ3D3W7A4F10 ZS7Q8O4X2J2文档编码:CJ10C2X5I1P7 HQ3D3W7A4F10 ZS7Q8O4X2J2文档编码:CJ10C2X5I1P7 HQ3D3W7A4F10 ZS7Q8O4X2J2文档编码:CJ10C2X5I1P7 HQ3D3W7A4F10 ZS7Q8O4X2J2文档编码:CJ10C2X5I1P7 HQ3D3W7A4F10 Z
5、S7Q8O4X2J2文档编码:CJ10C2X5I1P7 HQ3D3W7A4F10 ZS7Q8O4X2J2文档编码:CJ10C2X5I1P7 HQ3D3W7A4F10 ZS7Q8O4X2J2文档编码:CJ10C2X5I1P7 HQ3D3W7A4F10 ZS7Q8O4X2J2文档编码:CJ10C2X5I1P7 HQ3D3W7A4F10 ZS7Q8O4X2J2文档编码:CJ10C2X5I1P7 HQ3D3W7A4F10 ZS7Q8O4X2J2文档编码:CJ10C2X5I1P7 HQ3D3W7A4F10 ZS7Q8O4X2J2文档编码:CJ10C2X5I1P7 HQ3D3W7A4F10 ZS7Q8O4
6、X2J2文档编码:CJ10C2X5I1P7 HQ3D3W7A4F10 ZS7Q8O4X2J2文档编码:CJ10C2X5I1P7 HQ3D3W7A4F10 ZS7Q8O4X2J2文档编码:CJ10C2X5I1P7 HQ3D3W7A4F10 ZS7Q8O4X2J2文档编码:CJ10C2X5I1P7 HQ3D3W7A4F10 ZS7Q8O4X2J2文档编码:CJ10C2X5I1P7 HQ3D3W7A4F10 ZS7Q8O4X2J2文档编码:CJ10C2X5I1P7 HQ3D3W7A4F10 ZS7Q8O4X2J2文档编码:CJ10C2X5I1P7 HQ3D3W7A4F10 ZS7Q8O4X2J2文档
7、编码:CJ10C2X5I1P7 HQ3D3W7A4F10 ZS7Q8O4X2J2文档编码:CJ10C2X5I1P7 HQ3D3W7A4F10 ZS7Q8O4X2J2文档编码:CJ10C2X5I1P7 HQ3D3W7A4F10 ZS7Q8O4X2J2文档编码:CJ10C2X5I1P7 HQ3D3W7A4F10 ZS7Q8O4X2J2文档编码:CJ10C2X5I1P7 HQ3D3W7A4F10 ZS7Q8O4X2J2文档编码:CJ10C2X5I1P7 HQ3D3W7A4F10 ZS7Q8O4X2J2文档编码:CJ10C2X5I1P7 HQ3D3W7A4F10 ZS7Q8O4X2J2文档编码:CJ1
8、0C2X5I1P7 HQ3D3W7A4F10 ZS7Q8O4X2J2文档编码:CJ10C2X5I1P7 HQ3D3W7A4F10 ZS7Q8O4X2J2文档编码:CJ10C2X5I1P7 HQ3D3W7A4F10 ZS7Q8O4X2J2文档编码:CJ10C2X5I1P7 HQ3D3W7A4F10 ZS7Q8O4X2J2文档编码:CJ10C2X5I1P7 HQ3D3W7A4F10 ZS7Q8O4X2J2文档编码:CJ10C2X5I1P7 HQ3D3W7A4F10 ZS7Q8O4X2J2文档编码:CJ10C2X5I1P7 HQ3D3W7A4F10 ZS7Q8O4X2J2文档编码:CJ10C2X5I
9、1P7 HQ3D3W7A4F10 ZS7Q8O4X2J2文档编码:CJ10C2X5I1P7 HQ3D3W7A4F10 ZS7Q8O4X2J2文档编码:CJ10C2X5I1P7 HQ3D3W7A4F10 ZS7Q8O4X2J2文档编码:CJ10C2X5I1P7 HQ3D3W7A4F10 ZS7Q8O4X2J2文档编码:CJ10C2X5I1P7 HQ3D3W7A4F10 ZS7Q8O4X2J2文档编码:CJ10C2X5I1P7 HQ3D3W7A4F10 ZS7Q8O4X2J2文档编码:CJ10C2X5I1P7 HQ3D3W7A4F10 ZS7Q8O4X2J2文档编码:CJ10C2X5I1P7 HQ
10、3D3W7A4F10 ZS7Q8O4X2J2文档编码:CJ10C2X5I1P7 HQ3D3W7A4F10 ZS7Q8O4X2J2文档编码:CJ10C2X5I1P7 HQ3D3W7A4F10 ZS7Q8O4X2J2文档编码:CJ10C2X5I1P7 HQ3D3W7A4F10 ZS7Q8O4X2J2文档编码:CJ10C2X5I1P7 HQ3D3W7A4F10 ZS7Q8O4X2J2名师精编优秀教案分析:由题意可知,本题所给的是一组分母有理化的式子,因此,分母有理化后就可以达到化简的目的解:原式=(2-1+3-2+4-3+2002-2001)(2002+1)=(2002-1)(2002+1)=200
11、2-1=2001 五、归纳小结本节课应掌握:最简二次根式的概念及其运用六、布置作业 1教材 P15习题 212 3、7、102选用课时作业设计第三课时作业设计一、选择题 1如果xy(y0)是二次根式,那么,化为最简二次根式是()Axy(y0)Bxy(y0)Cxyy(y0)D以上都不对 2把(a-1)11a中根号外的(a-1)移入根号内得()A1a B1a C-1a D-1a3在下列各式中,化简正确的是()A53=315B12=122C4a b=a2bD32xx=x1x4化简3 227的结果是()文档编码:CJ10C2X5I1P7 HQ3D3W7A4F10 ZS7Q8O4X2J2文档编码:CJ1
12、0C2X5I1P7 HQ3D3W7A4F10 ZS7Q8O4X2J2文档编码:CJ10C2X5I1P7 HQ3D3W7A4F10 ZS7Q8O4X2J2文档编码:CJ10C2X5I1P7 HQ3D3W7A4F10 ZS7Q8O4X2J2文档编码:CJ10C2X5I1P7 HQ3D3W7A4F10 ZS7Q8O4X2J2文档编码:CJ10C2X5I1P7 HQ3D3W7A4F10 ZS7Q8O4X2J2文档编码:CJ10C2X5I1P7 HQ3D3W7A4F10 ZS7Q8O4X2J2文档编码:CJ10C2X5I1P7 HQ3D3W7A4F10 ZS7Q8O4X2J2文档编码:CJ10C2X5I
13、1P7 HQ3D3W7A4F10 ZS7Q8O4X2J2文档编码:CJ10C2X5I1P7 HQ3D3W7A4F10 ZS7Q8O4X2J2文档编码:CJ10C2X5I1P7 HQ3D3W7A4F10 ZS7Q8O4X2J2文档编码:CJ10C2X5I1P7 HQ3D3W7A4F10 ZS7Q8O4X2J2文档编码:CJ10C2X5I1P7 HQ3D3W7A4F10 ZS7Q8O4X2J2文档编码:CJ10C2X5I1P7 HQ3D3W7A4F10 ZS7Q8O4X2J2文档编码:CJ10C2X5I1P7 HQ3D3W7A4F10 ZS7Q8O4X2J2文档编码:CJ10C2X5I1P7 HQ
14、3D3W7A4F10 ZS7Q8O4X2J2文档编码:CJ10C2X5I1P7 HQ3D3W7A4F10 ZS7Q8O4X2J2文档编码:CJ10C2X5I1P7 HQ3D3W7A4F10 ZS7Q8O4X2J2文档编码:CJ10C2X5I1P7 HQ3D3W7A4F10 ZS7Q8O4X2J2文档编码:CJ10C2X5I1P7 HQ3D3W7A4F10 ZS7Q8O4X2J2文档编码:CJ10C2X5I1P7 HQ3D3W7A4F10 ZS7Q8O4X2J2文档编码:CJ10C2X5I1P7 HQ3D3W7A4F10 ZS7Q8O4X2J2文档编码:CJ10C2X5I1P7 HQ3D3W7A
15、4F10 ZS7Q8O4X2J2文档编码:CJ10C2X5I1P7 HQ3D3W7A4F10 ZS7Q8O4X2J2文档编码:CJ10C2X5I1P7 HQ3D3W7A4F10 ZS7Q8O4X2J2文档编码:CJ10C2X5I1P7 HQ3D3W7A4F10 ZS7Q8O4X2J2文档编码:CJ10C2X5I1P7 HQ3D3W7A4F10 ZS7Q8O4X2J2文档编码:CJ10C2X5I1P7 HQ3D3W7A4F10 ZS7Q8O4X2J2文档编码:CJ10C2X5I1P7 HQ3D3W7A4F10 ZS7Q8O4X2J2文档编码:CJ10C2X5I1P7 HQ3D3W7A4F10 Z
16、S7Q8O4X2J2文档编码:CJ10C2X5I1P7 HQ3D3W7A4F10 ZS7Q8O4X2J2文档编码:CJ10C2X5I1P7 HQ3D3W7A4F10 ZS7Q8O4X2J2文档编码:CJ10C2X5I1P7 HQ3D3W7A4F10 ZS7Q8O4X2J2文档编码:CJ10C2X5I1P7 HQ3D3W7A4F10 ZS7Q8O4X2J2文档编码:CJ10C2X5I1P7 HQ3D3W7A4F10 ZS7Q8O4X2J2文档编码:CJ10C2X5I1P7 HQ3D3W7A4F10 ZS7Q8O4X2J2文档编码:CJ10C2X5I1P7 HQ3D3W7A4F10 ZS7Q8O4
17、X2J2文档编码:CJ10C2X5I1P7 HQ3D3W7A4F10 ZS7Q8O4X2J2文档编码:CJ10C2X5I1P7 HQ3D3W7A4F10 ZS7Q8O4X2J2文档编码:CJ10C2X5I1P7 HQ3D3W7A4F10 ZS7Q8O4X2J2文档编码:CJ10C2X5I1P7 HQ3D3W7A4F10 ZS7Q8O4X2J2文档编码:CJ10C2X5I1P7 HQ3D3W7A4F10 ZS7Q8O4X2J2文档编码:CJ10C2X5I1P7 HQ3D3W7A4F10 ZS7Q8O4X2J2文档编码:CJ10C2X5I1P7 HQ3D3W7A4F10 ZS7Q8O4X2J2文档
18、编码:CJ10C2X5I1P7 HQ3D3W7A4F10 ZS7Q8O4X2J2文档编码:CJ10C2X5I1P7 HQ3D3W7A4F10 ZS7Q8O4X2J2文档编码:CJ10C2X5I1P7 HQ3D3W7A4F10 ZS7Q8O4X2J2文档编码:CJ10C2X5I1P7 HQ3D3W7A4F10 ZS7Q8O4X2J2名师精编优秀教案A-23B-23C-63D-2二、填空题 1化简422xx y=_(x0)2a21aa化简二次根式号后的结果是_三、综合提高题 1已知 a 为实数,化简:3a-a1a,阅读下面的解答过程,请判断是否正确?若不正确,?请写出正确的解答过程:解:3a-a1
19、a=aa-a 1aa=(a-1)a 2若 x、y 为实数,且y=224412xxx,求xyxy的值答案:一、1C 2 D 3.C 4.C 二、1x22xy 2 -1a三、1不正确,正确解答:因为3010aa,所以 a0,原式2a a-a 2aa=a2a-a 2aa=-aa+a=(1-a)a2224040 xxx-4=0,x=2,但 x+20,x=2,y=14文档编码:CJ10C2X5I1P7 HQ3D3W7A4F10 ZS7Q8O4X2J2文档编码:CJ10C2X5I1P7 HQ3D3W7A4F10 ZS7Q8O4X2J2文档编码:CJ10C2X5I1P7 HQ3D3W7A4F10 ZS7Q8
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