十字相乘课堂

一、计算：)9)(5(xx(1)(2)(3)6)(23(xx(4)18)(4(xx45142xx138292xx72142xx)(bxax)5)(12(xx6072xxabxbax)(2)9)(5(xx)6)(23(xx)18)(4(xx45142xx138292xx72142xx)5)(12(xx6072xx)9)(5(xx)6)(23(xx)18)(4(xx45142xx138292xx72142xx)5)(12(xx6072xx762xx)1)(7(xxxx7171步骤：xxx67 1582xx)3)(5(xxxx35xxx8)5()3(qpxx2bapabq,)9)(5(xx)6)(23(xx)18)(4(xx)5)(12(xx6072xx45142xx72142xx138292xx_342 xx_322 xx2092 yy_56102tt_-例2把;分解因式152xx2;分解因式107aa把3例2xx3-5原式:解;分解因式107abba把4例22;分解因式60m3m3m把5例23(x+3)(x-5)aa52解:原式=(a+5)(a+2)abab-2-5解:原式=(ab-2)(ab-5)解:原式=20)m3m(m2mm-54=3m(m-5)(m+4)2a+5a=7a-5x+3x=-2x-5ab-2ab=-7ab4m-5m=-m1、2、1662xx1662xx28xx1662xx（1）6=（2）-6=（3）12=（4）-12=（5）24=（6）-24=23 或(-2)(-3)或16或(-1)(-6)1(-6)或-16或2(-3)或3(-2)1 12或(-1)(-12)或2 6或(-2)(-6)或34 或(-3)(-4)1(-12)或(-1)12或2(-6)或(-2)6或3(-4)或(-3)41 24或(-1)(-24)或2 12或(-2)(-12)或38或(-3)(-8)或4 6或(-4)(-6)1(-24)或(-1)24或2(-12)或(-2)12或3(-8)或(-3)8或4(-6)或(-4)6练习二丶把下列各式分解因式:;2463t 6.;2 x.5;365p 4.;187m .3;127y 2.;34 x.1222222tyxyypmyx2)xy(x原式:解28)2t3(t原式:解2提高题1把下列各式分解因式;7)(3x3x)(x 3.;2xyy3xy x2.;28x3x x1.222322323428)3x(xx原式:解22xx4-74x-7x=-3x2x)2y3xyxy(x原式:解22xx-y-2y-2xy-xy=-3xy=xy(x-2y)(x-y)(x+4)(x-7)7)(3x3x)7)(x(3x3x)(x原式:解227)3x3x7)(x3x3x(x227)6x7)(x(x22xx1-7-7x+x=-6x7)(x2(x+1)(x-7)121315222xxxx301718322xyxy42132aa