comment calculer (a-b) au cube

Identite remarquable. a^3-3a^2b+3ab^2-b^3

(a-b) (a-b) (a-b) = (a-b) (a²+b²-2ab) = a^3+ab²-2a²b -a²b-b^3+2ab² = a^3 -b^3 +3ab²- 3a²b