`3x^4-8x^3-10x^2+8x-5`
`=3x^4-2x^3+x^2-6x^3+4x^2-2x-15x^2+10x-5`
`=(3x^4-2x^3+x^2)-(6x^3-4x^2+2x)-(15x^2-10x+5)`
`=x^2(3x^2-2x+1)-2x(3x^2-2x+1)-5(3x^2-2x+1)`
`=(3x^2-2x+1)(x^2-2x-5).`
Có: `(3x^4-8x^3-10x^2+8x-5):(3x^2-2x+1)`
`⇔(3x^2-2x+1)(x^2-2x-5):(3x^2-2x+1)=x^2-2x-5.`
Vậy `(3x^4-8x^3-10x^2+8x-5):(3x^2-2x+1)=x^2-2x-5.`