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8.2整式乘法第1课时单项式与单项式相乘知识要点基础练知识点 单项式与单项式相乘1.计算3x3(-2x7)的结果是(A)A.-6x10B.-6x21C.-x10D.x10【变式拓展】计算(-x2y)3(-2xy2)=2x7y5.2.若-2a2bma2b2=6a4b3,则m的值为(B)A.3B.-3C.8D.-43.4x2xy3=8x2y3.4.计算:(1)(-4x5)(-2x4);解:原式=8x9.(2)23a3b-32ab2c.解:原式=-a4b3c.综合能力提升练5.下列运算正确的是(B)A.4x33x2=12x6B.(-3a4)(-4a3)=12a7C.3a45a3=8a7D.(-a)(-2a)3(-3a)2=-72a66.计算(3103)2(-2102)3的结果是(D)A.61012B.7.21013C.-7.21012D.-7.210137.计算2xy-12x2y2z(-3x3y2)的结果是(A)A.3x6y5zB.-3x6y5zC.3x5y5zD.3x6y58.已知A=3x2,B=-2xy2,C=-x2y2,则AB2C=-12x6y6.9.计算:(1)(2x2y)(3xy2)-4xy(xy)2;解:原式=6x3y3-4x3y3=2x3y3.(2)25x2y3516xyz(-2x2y).解:原式=25516(-2)x5y5z=-14x5y5z.10.若实数x,y满足|2x-3y+1|+x+3y+5=0,求代数式(-2xy)2(-y3)3xy2的值.解:根据非负数性质得2x-3y+1=0,x+3y+5=0,解得x=-2,y=-1.(-2xy)2(-y3)3xy2=4x2y2(-y3)3xy2=-12x3y7=-12(-2)3(-1)7=-96.11.已知长方体的长为8107 cm,宽为6105 cm,高为5109 cm,求长方体的体积.解:(8107)(6105)(5109)=2401021=2.41023 (cm3).答:长方体的体积是2.41023 cm3.拓展探究突破练12.已知(-2xm+1y2n-1)(5xnym)=-10x4y4,求-2m2n-12m3n22的值.解:由(-2xm+1y2n-1)(5xnym)=-10xm+n+1ym+2n-1=-10x4y4,可得m+n+1=4,m+2n-1=4,解得m=1,n=2,则-2m2n-12m3n22=-12m8n5=-16.
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