-3(2分之1x的3次方-3分之1y的3次方+6分之1)+2(3分之1x的3次方-2分之1y的3次方+4分之1)-3(1/2x^3-1/3y^3+1/6)+2(1/3x^3-1/2y^3+1/4)=-3/2x^3+y^3-1/2+2/3x^3-y^3+1/2=(-3/2+2/3)x^2+(1-1)y^3+(-1/2+1/2)=-5/6x^3...