提公因式法.doc

提公因式法
班级:_______ 姓名:_______
一、请你填一填
(1)单项式-12x12y3与8x10y6的公因式是________.
(2)-xy2(x+y)3+x(x+y)2的公因式是________.
(3)把4ab2-2ab+8a分解因式得________.
(4)5(m-n)4-(n-m)5可以写成________与________的乘积.
二、认真选一选
(1)多项式8xmyn-1-12x3myn的公因式是( )
-1 -1
(2)把多项式-4a3+4a2-16a分解因式( )
A.-a(4a2-4a+16) (-4a2+4a-16)
C.-4(a3-a2+4a) D.-4a(a2-a+4)

-b+5ac +b-5ac
-b+ac +b-ac
(4)用提取公因式法分解因式正确的是( )
-9a2b2=3abc(4-3ab)
-3xy+6y=3y(x2-x+2y)
C.-a2+ab-ac=-a(a-b+c)
+5xy-y=y(x2+5x)
三、请分解因式
(1)x(x-y)-y(y-x)
(2)-12x3+12x2y-3xy2
(3)(x+y)2+mx+my
(4)a(x-a)(x+y)2-b(x-a)2(x+y)
四、好好想一想
.
①5x2-15x=0
②5x(x-2)-4(2-x)=0
=-5,a+b+c=-,求代数式a2(-b-c)-(c+b)的值.
参考答案
一、(1)4x10y3 (2)x(x+y)2 (3)2a(2b2-b+4)(4)(m-n)4 (5+m-n)
二、(1)D (2)D (3)A (4)C
三、(1)x(x-y)-y(y-x)=(x-y)(x+y)
(2)-12x3+12x2y-3x