(3х+2у)^3=(3x)^3+3*(3x)^2*2y+3*3x*(2y)^2+(2y)^3 = 27x^3+54x^2y+36xy^2+8y^3
(2-3x)^3=2^3-3*2^2*3x+3*2*(3x)^2-(3x)^3=8-36x+54x^2-27x^3
(3x-4)^3= (3x)^3-3*(3x)^2*4+3*3x*4^2-4^3=27x^3-108x^2+144x-64
(x+3y)^3=x^3+3*x^2*3y+3*x*(3y)^2+(3y)^3=x^3+9x^2*y+27xy^2+27y^3