B + B/A = 1⇒ (A2 + B2)/AB = 1⇒ (A2 + B2) = ABAs we know,(A3 + B3) = (A + B) (A2 + B2 - AB)⇒ (A3 + B3) = (A + B) (AB - AB)⇒ (A3 + B3) = (A + B) × 0⇒ (A3 + B3) = 0