Cho các đa thức C=x^3+4x^3y-6xy^3-4xy^2+5x^2y^2

$C-A-B$ 

$=x^3+4x^{3}y-6x{y}^3-4x{y}^2+5x^2{y}^2-5x^{3}y+4x{y}^2+6x^2{y}^2+8x{y}^3-x{y}^2+4x^2{y}^2$ 

$=x^3-x^{3}y+2x{y}^3-x{y}^2+15x^2{y}^2$