Đáp án:
$x^7+x^2+1$
$=\left(x^7-x\right)+\left(x^2+x+1\right)$
$=\left(x^7-x\right)+\left(x^2+x+1\right)$
$=x\left(x^3-1\right)\left(x^3+1\right)+\left(x^2+x+1\right)$
$=x\left(x-1\right)\left(x^2+x+1\right)\left(x^3+1\right)+\left(x^2+x+1\right)$
$=\left(x^2+x+1\right)\left[x\left(x-1\right)\left(x^3+1\right)+1\right]$
$=\left(x^2+x+1\right)\left[\left(x^2-x\right)\left(x^3+1\right)+1\right]$
$=\left(x^2+x+1\right)\left(x^5-x^4+x^2-x+1\right)$
