b) a^3 + b^3 = (a + b)[(a – b)^2 + ab];
b) a3 + b3 = (a + b)[(a – b)2 + ab];
b) a3 + b3 = (a + b)(a2 ‒ ab + b2)
= (a + b)(a2 ‒ 2ab + b2 + ab)
= (a + b)[(a ‒b)2 + ab].