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