Đáp án:
`x^5 - x^4 y - xy^4 + y^5`
`= (x^5 - x^4 y) - (xy^4 - y^5)`
`= x^4 (x - y) - y^4 (x - y)`
`= (x - y)(x^4 - y^4)`
`= (x - y)[(x^2)^2 - (y^2)^2]`
`= (x - y)(x^2 - y^2)(x^2 + y^2)`
`= (x - y)(x - y)(x + y)(x^2 + y^2)`
`= (x - y)^2 (x + y)(x^2 + y^2)`
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`x^6 y - x^4 y^3 - x^3 y^4 + xy^6`
`= (x^6 y - x^4 y^3) - (x^3 y^4 - xy^6)`
`= x^4 y(x^2 - y^2) - xy^4 (x^2 - y^2)`
`= (x^2 - y^2)(x^4 y - xy^4)`
`= (x - y)(x + y)(x^3 - y^3).xy`
`= xy(x - y)(x + y)(x - y)(x^2 + xy + y^2)`
`= xy(x - y)^2 (x + y)(x^2 + xy + y^2)`
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`2x^3 + 4x^2 y + 2xy^2 - 18x`
`= 2x(x^2 + 2xy + y^2 - 9)`
`= 2x[(x^2 + 2xy + y^2) - 9]`
`= 2x[(x + y)^2 - 3^2]`
`= 2x(x + y + 3)(x + y - 3)`
