Докажите тождество)

(a+b) ^2 (a-b) - 2ab (b-a) - 6ab (a-b) = (a-b) ^3

(a+b) ^2 * a - (a+b) ^2 * b - 2ab^2 + 2a^2b - 6a^2b + 6ab^2 = (a^2 + 2ab + b^2) * a - (a^2 + 2ab + b^2) * b - 2ab^2 + 2a^2b - 6a^2b + 6ab^2 = a^3 + 2a^2b + ab^2 - (a^2 + 2ab + b^2) * b - 2ab^2 + 2a^2b - 6a^2b + 6ab^2 = a^3 + 2a^2b + 5ab^2 + (-a^2 - 2ab - b^2) * b = a^3 + 2a^2b + 5ab^2 - a^2b - 2ab^2 - b^3 = a^3 - 3a^2b + 3ab^2 - b^3 = (a - b) ^3