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^

问题描述:

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...