×　(a±b)^2=a^2±2ab+b^2
×　(a±b)^3=a^3±3a^2b+3ab^2±b^3

(a±b)^2=(a^2)±2ab+b^2
(a±b)^3=(a^3)±3(a^2)b+3a(b^2)±b^3