八年级数学上册第十四章整式的乘法与因式分解周滚动练14.2-14.3PPT课件新人教版.ppt

单击此处编辑母版标题样式,单击此处编辑母版文本样式,第二级,第三级,第四级,第五级,*,*,*,周滚动练,(14,.,2,14,.,3 ),一、选择题,(,每小题,4,分,共,32,分,),1,.,运用乘法公式计算,(3,m+,2 )(3,m-,2 ),的结果是,(,B,),A.3,m,2,-,2 B.9,m,2,-,4,C.9,m,2,+,4 D.3,m,2,+,2,2,.,(,常德中考,),下列各式由左到右的变形中,属于分解因式的是,(,C,),A.,a,(,m+n,),=,am+an,B.,a,2,-b,2,-c,2,=,(,a-b,)(,a+b,),-c,2,C.10,x,2,-,5,x=,5,x,(2,x-,1 ),D.,x,2,-,16,+,6,x=,(,x+,4 )(,x-,4 ),+,6,x,3,.,多项式,x,2,-,1,与多项式,x,2,-,2,x+,1,的公因式是,(,A,),A.,x-,1B.,x+,1,C.,x,2,-,1D.(,x-,1 ),2,4,.,下列关于,96,2,的计算方法正确的是,(,D,),A.96,2,=,(100,-,4 ),2,=,100,2,-,4,2,=,9984,B.96,2,=,(95,+,1 )(95,-,1 ),=,95,2,-,1,=,9024,C.96,2,=,(90,+,6 ),2,=,90,2,+,6,2,=,8136,D.96,2,=,(100,-,4 ),2,=,100,2,-,2,4,100,+,4,2,=,9216,5,.,下列多项式中,能用公式法分解因式的是,(,A,),A.,-m,2,+n,2,B.,a,2,-,2,ab-b,2,C.,m,2,+n,2,D.,-a,2,-b,2,6,.,把代数式,ax,2,-,4,ax+,4,a,分解因式,下列结果中正确的是,(,B,),A.,a,(,x+,2 ),2,B.,a,(,x-,2 ),2,C.,a,(,x-,4 ),2,D.,a,(,x-,2 )(,x+,2 ),7,.,已知,a+b,=,3,ab=,2,则,(,a,2,+b,2,),2,的值为,(,C,),A.9B.16,C.25D.36,8,.,如图,长方形,ABCD,的周长为,16,以长方形四条边为边长向外作四个正方形,若四个正方形面积之和为,68,则长方形,ABCD,的面积为,(,B,),A.12B.15,C.18D.20,三、解答题,(,共,48,分,),14,.,(9,分,),因式分,解,:,(1 )2,x,2,-,8;,解,:,原式,=,2(,x+,2 )(,x-,2 ),.,(2 ),m,3,n-,10,m,2,n+,25,mn,;,解,:,原式,=,mn,(,m-,5 ),2,.,(3 ),a,2,(,a-b,),+,9(,b-a,),.,解,:,原式,=,(,a-b,)(,a+,3 )(,a-,3 ),.,15,.,(5,分,)(,大庆中考,),已知,a+b,=,3,ab=,2,求代数式,a,3,b+,2,a,2,b,2,+ab,3,的值,.,解,:,a,3,b+,2,a,2,b,2,+ab,3,=,ab,(,a,2,+,2,ab+b,2,),=,ab,(,a+b,),2,将,a+b,=,3,ab=,2,代入得,ab,(,a+b,),2,=,2,3,2,=,18,.,故代数式,a,3,b+,2,a,2,b,2,+ab,3,的值是,18,.,16,.,(8,分,),已知,x,2,-,2,x-,7,=,0,求,(,x-,2 ),2,+,(,x+,3 )(,x-,3 ),的值,.,解,:(,x-,2 ),2,+,(,x+,3 )(,x-,3 ),=x,2,-,4,x+,4,+x,2,-,9,=,2,x,2,-,4,x-,5,x,2,-,2,x-,7,=,0,x,2,-,2,x=,7,.,原式,=,2(,x,2,-,2,x,),-,5,=,9,.,17,.,(8,分,),已知,a,b,c,是,ABC,的三边长,且,a,2,+,2,b,2,+c,2,-,2,b,(,a+c,),=,0,你能判断,ABC,的形状吗,?,请说明理由,.,解,:,a,2,+,2,b,2,+c,2,-,2,b,(,a+c,),=,0,(,a,2,+b,2,-,2,ab,),+b,2,+c,2,-,2,bc=,0,即,(,a-b,),2,+,(,b-c,),2,=,0,a-b=,0,b-c=,0,即,a=b=c,ABC,为等边三角形,.,18,.,(8,分,),利用乘法公式进行简便计算,:,(1 )202,2,;,解,:,原式,=,(200,+,2 ),2,=,40000,+,800,+,4,=,40804,.,(2 )101,99,-,99,.,5,2,.,解,:,原式,=,(100,+,1 ),(100,-,1 ),-,=,100,2,-,1,2,-,=,100,2,-,1,-,100,2,+,100,-,0,.,25,=,98,.,75,.,