Đáp án:
Đề ở phần cmt:
`2.(x^2-6x+1)^2+5.(x^2-6x+1).(x^2+1)+2.(x^2+1)^2`
`=2.(x^2-6x+1)^2+(x^2-6x+1).(x^2+1)+4.(x^2-6x+1).(x^2+1)+2.(x^2+1)^2`
`=[2.(x^2-6x+1)^2+(x^2-6x+1).(x^2+1)]+[4.(x^2-6x+1).(x^2+1)+2.(x^2+1)^2]`
`=(x^2-6x+1).[2.(x^2-6x+1)+(x^2+1)]+2.(x^2+1).[2.(x^2-6x+1)+(x^2+1)]`
`=[(x^2-6x+1)+2.(x^2+1)].[2.(x^2-6x+1)+(x^2+1)]`
`=(x^2-6x+1+2x^2+2).(2x^2-12x+2+x^2+1)`
`=(3x^2-6x+3).(3x^2-12x+3)`
`=3.(x^2-2x+1).3.(x^2-4x+1)`
`=9.(x^2-2x+1).(x^2-4x+1)`
`=9.(x-1).(x-1).(x^2-4x+1)`
