(x+y)^2-9(x-y)^2分解因式

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(x+y)^2-9(x-y)^2分解因式

(x+y)^2-9(x-y)^2分解因式
(x+y)^2-9(x-y)^2分解因式

(x+y)^2-9(x-y)^2分解因式
(x+y)^2-9(x-y)^2
=(x+y)²-(3x-3y)²
=[(x+y)+(3x-3y)][(x+y)-(3x-3y)]
=(4x-2y)(-2x+4y)
=-4(2x-y)(x-2y)

(x+y)^2-9(x-y)^2
=(x+y)^2-[3(x-y)]^2
=[(x+y)+3(x-y)][(x+y)-3(x-y)]
=(4x-2y)(-2x+4y)
=-4(2x-y)(x-2y)