(3x+yz)(9x^2 - 3xyz + y^2z^2) = (3x)(9x^2) + (3x)(-3xyz) + (3x)(y^2z^2) + (yz)(9x^2) + (yz)(-3xyz) + (yz)(y^2z^227x^3 - 9x^2yz + 3xy^2z^2 + 9x^2yz - 3xyz^2 + y^3z^= 27x^3 + 3xy^2z^2 - 3xyz^2 + y^3z^3
(3x+yz)(9x^2 - 3xyz + y^2z^2) = (3x)(9x^2) + (3x)(-3xyz) + (3x)(y^2z^2) + (yz)(9x^2) + (yz)(-3xyz) + (yz)(y^2z^2
27x^3 - 9x^2yz + 3xy^2z^2 + 9x^2yz - 3xyz^2 + y^3z^
= 27x^3 + 3xy^2z^2 - 3xyz^2 + y^3z^3