Đáp án:
`6)x^3-x^2y-y^2x+y^3`
`= x^2 ( x - y) - y^2 ( x-y)`
`= (x^2 - y^2)(x-y)`
`= (x-y)^2(x+y)`
`7)x^3-3x^2+3x-1-y^3`
`=(x-1)^3 - y^3`
`= (x-1-y)[(x-1)^2 +(x-1).y + y^2]`
`= (x-y-1)(x^2 - 2x + 1 + xy - y + y^2)`
`= (x-y-1)(x^2 + y^2 - 2x + xy - y + 1)`
`8)x^3+x^2-4x-4`
`= x^2 ( x + 1) - 4(x+1)`
`= (x-2)(x+2)(x+1)`
`9)x^4+2x^3+x^2-y^2`
`=(x^2 + x)^2 - y^2`
`= (x^2 + x + y)(x^2 + x - y)`
`10)x^3-4x^2-4x+1`
`= x^3 - 5x^2 + x + x^2 - 5x + 1`
`= x(x^2 - 5x +1 ) + (x^2 - 5x + 1)`
`=(x+1)(x^2 - 5x + 1)`