冀教版（2024）新教材八年级数学上册第十二章12.2.1 分式的乘法 同步练习.docx

12.2　分式的乘除课时1　分式的乘法知识点 分式的乘法1.计算:-3xy2·2x18y3= (　　)A.-x23y B.-x2y C.-x23y2 D.-x3y2.计算x2-4x+1·x+1x-2的结果是 (　　)A.x+1 B.x+2 C.1x+1 D.1x-23.计算-b2a·(-4a3b)·(-2a3b)的结果是 (　　)A.-ba B.ba C.-b4a D.-4a9b4.当分式a2x-a2yx2-y2·(x+y)2ax+ay的值等于-5时,a的值为 (　　)A.5 B.-5 C.15 D.-155.计算:a2-1a·a2(a-1)2=　　　　.6.计算:(-2a2b3c)2=　　　　.7.计算:x2+1x-6·x2-36x3+x=　　　　.8.若ab=2,bc=6,则ac=　　　　.9.把a克盐溶化在b克水中,取这样的盐水xa克,则其中含盐　　　　克.10.计算:(1)8x2·(-3x4y3)·(-6zx2y);(2)2x+2y5a2b·10ab2x2-y2;(3)x2y-x3x2+2xy+y2·x-yx·x+yx2-2xy+y2.11.先化简,再求值:(1)a-bab·2a2b2a2-b2,其中a=1,b=2;(2)x-1x+2·x2-4x2-2x+1,其中|x|=2.12.已知A=2x+yx2-2xy+y2·(x-y).(1)化简A;(2)若x2-6xy+9y2=0,求A的值.参考答案1.A　【解析】　-3xy2·2x18y3=-6x2y218y3=-x23y.故选A.2.B　【解析】　x2-4x+1·x+1x-2=(x+2)(x-2)x+1·x+1x-2=x+2.故选B.3.D　【解析】　 -b2a·(-4a3b)·(-2a3b)=-8a2b18ab2=-4a9b.故选D.4.B　【解析】　∵a2x-a2yx2-y2·(x+y)2ax+ay=a2(x-y)(x+y)(x-y)·(x+y)2a(x+y)=a,∴a=-5.故选B.5. a(a+1)a-1　【解析】　a2-1a·a2(a-1)2= (a-1)(a+1)a· a2(a-1)2= a(a+1)a-1.6.4a4b29c27. x+6x　【解析】　x2+1x-6·x2-36x3+x=x2+1x-6·(x+6)(x-6)x(x2+1)=x+6x.8.12　【解析】　解法一　根据分式的乘法法则,得ab×bc=ac=2×6=12.解法二　由ab=2,可以得到a=2b,同理可以得到c=b6,所以ac=2bb6=12.9. xa+b　【解析】　a克盐溶化在b克水中,水中盐的占比为aa+b,则取这样的盐水xa克,其中含盐xa·aa+b=xa+b(克).10.【解析】　(1)8x2·(-3x4y3)·(-6zx2y)=8x2·3x·6z4y3·x2y=36xzy4.(2)2x+2y5a2b·10ab2x2-y2=2(x+y)5a2b·10ab2(x+y)(x-y)=4bax-ay.(3)x2y-x3x2+2xy+y2·x-yx·x+yx2-2xy+y2=-x2(x-y)(x+y)2·x-yx·x+y(x-y)2=-xx+y.11.【解析】　(1)a-bab·2a2b2a2-b2=a-bab·2a2b2(a+b)(a-b)=2aba+b,当a=1,b=2时,原式=2aba+b=2×1×21+2=43.(2)x-1x+2·x2-4x2-2x+1=x-1x+2·(x+2)(x-2)(x-1)2=x-2x-1.∵|x|=2,∴x=±2,又∵x+2≠0,且x-1≠0,∴x≠-2,且x≠1,∴x=2.当x=2时,原式=x-2x-1=2-22-1=0.12.【解析】　(1)A=2x+yx2-2xy+y2·(x-y)=2x+y(x-y)2·(x-y)=2x+yx-y.(2)∵x2-6xy+9y2=0,∴(x-3y)2=0,则x-3y=0,故x=3y,则A=2x+yx-y=6y+y3y-y=72.。