a^3+b^3= (a+b)(a^2-ab+b^2)
a^3-a^3= (a-b) (a^2+ab+b^2)
(a+b)^3= a^3+3a*(b^2)+3(a^2)*b+b^3
(a-b)^3= a^3+3a*(b^2)-3(a^2)*b-b^3