A cura di: Alfredo Bochicchio

$6x^2z-12x^2yz^2+18xy^2z^2$
$6xyz(y-2xz+3yz)$
$-8x^2y^3-10x^3y^2+6x^4y^3$
$2x^2y^2(-4y-5x+3x^2y)$