2019年春七年级数学下册第8章整式乘法和因式分解8.2整式乘法第4课时多项式除以单项式教学课件（新版）沪科版.pptx

1、第8章 整式乘法与因式分解,8.2 整式乘法,知识点 多项式除以单项式1.计算( 2x2-x )x的结果是( D ) A.x B.2x C.2x+1 D.2x-1 2.计算( 6x2y-3x )( -3x )的结果是( C ) A.-2xy B.-2x+1 C.-2xy+1 D.-2xy-1 3.计算:( 4x2y-6xy2-2xy )( -2xy )= -2x+3y+1 . 4.填空:( a2-ab+a )a=a-b+1.,5.计算y2-y( y-x )+xx的结果是( C ) A.y B.-y C.y+1 D.y-1 【变式拓展】计算2x( 3x-1 )-6( x2+x )( -x )=

2、8 . 6.若( 21x3y+-3xy3 )( -3xy )=-7x2+2x+y2,则“”应是( C ) A.-2x2 B.2x2 C.-6x2y D.6x2y,10.计算: ( 1 )5xy2( x2-3xy )-( -5x2y2 )2( -5x2y );,解:原式=-xy+3y2+5x2y3.,( 2 )2( x+y )3-4( x+y )2-x-y( x+y ).,解:原式=2x2+4xy+2y2-4x-4y-1.,11.先化简,后求值:( a2b-2ab2-b3 )b-a( a-b ),其中a=-1,b=-2.,解:原式=a2-2ab-b2-a2+ab=-ab-b2. 当a=-1,b=-2时,原式=-( -1 )( -2 )-( -2 )2=-2-4=-6.,12.观察下列各式: ( x2-1 )( x-1 )=x+1; ( x3-1 )( x-1 )=x2+x+1; ( x4-1 )( x-1 )=x3+x2+x+1; ( x5-1 )( x-1 )=x4+x3+x2+x+1; ( 1 )你能得到( xn-1 )( x-1 )的结果吗? ( 2 )试计算:1+2+22+262+263.,解:( 1 )xn-1+xn-2+x2+x+1. ( 2 )1+2+22+262+263=( 264-1 )( 2-1 )=264-1.,