因式分解.（1）3a平方+bc-3ac-ab （2）a平方m+bn-an-abm （3）4xy-3xz+8y-6z （4
3个回答
(1)3a^2+bc-3ac-ab
=(3a^2-3ac)-(ab-bc)
=3a(a-c)-b(a-c)
=(3a-b)(a-c)
(2)a^2m+bn-an-abm
=(a^2m-abm)-(an-bn)
=am(a-b)-n(a-b)
=(am-n)(a-b)
(3)4xy-3xz+8y-6z
=(4xy-3xz)+(8y-6z)
=x(4y-3z)+2(4y-3z)
=(x+2)(4y-3z)
(4)x^3+3x^2+3x+9
=x^2(x+3)+3(x+3)
=(x^2+3)(x+3)
(5)题目不对
(6)4x^2-4xy+y^2-a^2
=(2x-y)^2-a^2
=(2x-y-a)(2x-y+a)
(7)5ax+7ay-5bx-7by
=a(5x+7y)-b(5x+7y)
=(a-b)(5x+7y)
(8)1-m^2-n^2+2mn
=1-(m-n)^2
=(1-m+n)(1+m-n)
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