(x-y)^3-8y^3分解因式

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(x-y)^3-8y^3分解因式

(x-y)^3-8y^3分解因式
(x-y)^3-8y^3分解因式

(x-y)^3-8y^3分解因式
原式=(x-y-2y)[(x-y)²+2y(x-y)+4y²]
=(x-3y)(x²-2xy+y²+2xy-2y²+4y²)
=(x-3y)(x²+3y²)

=(x-y-2y)[(x-y)^2+2y(x-y)+(2y)^2]=...........

(x-y)^3-8y^3
=[(x-y)-2y][(x-y)^2+(x-y)*2y+(2y)^2]
=(x-3y)(x^2-2xy+y^2+2xy-2y^2+4y^2)
=(x-3y)(x^2+3y^2)

(x-y)^3-8y^3
=(x-y-2y)(x-y+2y)(x-y-2y)
=(x-3y)^2(x+y)

(x-y)^3-8y^3
=(x-y-2y)((x-y)²+4y²+2y(x-y))
=(x-3y)(x²+3y²)

用公式 a^3-b^3=(a-b)(a^2+ab+b^2)
原式=(x-y)^3-(2y)^3
=(x-3y)[(x^2-2xy+y^2+2xy-2y^2+4y^2)]

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

x^3-3x^2y+3xy^2-y^3-8y^3