Câu `2` :
`(x-3)(2x^2 - 3x+5)`
`=2x^3 - 9x^2 + 14x-5`
`(2x-1)(x^2 - 4x + 5)`
`=2x^3 - 9x^2 + 14x-5`
Câu `3` :
`(x+2)(x^2 -2x+4)-(x-1)^3 - 3(x-1)(x+1)=3`
`⇔x^3 + 2^3 - x^3 + 3x^2 -3x+1+3.(x^2 - 1) =3`
`⇔x^3 + 8-x^3 - 3x^2 - 3x - 1 + 3x^2 - 3 =3`
`⇔-3x=9`
`⇔x=3`
`(x-2)(x^2 + 2x+4)-(x+1)^3 + 3(x+1)(x-1)=0`
`⇔x^3 - 8 - x^3 - 3x^2 -3x-1+3x^2 - 3=0`
`⇔x=-4`