~ Bạn tham khảo ~
`c, a^3b^3 - 1`
`= (ab)^3 - 1^3`
`= (ab-1)(a^2b^2 + ab + 1)`
`d, x^2(y-z) + y^2(z-x) + z^2(x-y)`
`= x^2(y-z) + y^2z - y^2x + z^2x - z^2y`
`= x^2(y-z) + yz(y-z) - x(y^2 - z^2)`
`= x^2(y-z) + yz(y-z) - x(y-z)(y+z)`
`= (y-z)(x^2 + yz - xy - xz)`
`= (y-z)[x(x-z) + y(z-x)]`
`= (y-z)[x(x-z) - y(x-z)]`
`= (y-z)(x-y)(x-z)`