We know that,a3 + b3 + c3 – 3abc = (a + b + c) (a2 + b2 + c2 – ab – bc – ca)]Using this formula, we get= (a)3 + (2b)3 + (c)3 – 3 (a) (2b) (c)= ( + 2b + c) [()2 + (2b)2 + (c)2 – () (2b) – (2b) (c) – (c) (a)]= ( + 2b + c) (2a2 + 8b2 + c2 – 4ab – 2bc – ac)