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分解因式:(1)-3xy-9y^2-1/4x^2 (2)14a^2b-49a^3b-ab (3)a^4-2a^2b^2+

来源:学生作业帮 编辑:作业帮 分类:数学作业 时间:2024/05/14 12:10:26
分解因式:(1)-3xy-9y^2-1/4x^2 (2)14a^2b-49a^3b-ab (3)a^4-2a^2b^2+b^4 (4)(x+y)^2+4(x-y)^2-4(x^2y^
会几个打几个,
(4)(x+y)^2+4(x-y)^2-4(x^2y^2)
(1)-3xy-9y^2-1/4x^2
=-4(12xy+36y^2+x^2)
=-4(x+6y)^2
(2)14a^2b-49a^3b-ab
=-ab(-14a+49a^2+1)
=-ab(7a-1)^2
(3)a^4-2a^2b^2+b^4
=(a^2-b^2)^2
=[(a+b)(a-b)]^2
=(a+b)^2(a-b)^2
(4)(x+y)^2+4(x-y)^2-4(x^2-y^2)
=(x+y)^2-4(x^2-y^2)+4(x-y)^2
=(x+y)^2-4(x-y)(x+y)+4(x-y)^2
=[(x+y)-2(x-y)]^2
=(x+y-2x+2y)^2
=(3y-x)^2