VITEEE 2015 Paper

[a + b, b + c, c + a]
= (a + b). [(b + c) x (c + a)]
= (a + b).[bxc + bxa + cxc+cxa]
= (a + b). (b x c + b x a + c x a) [ Since c x c = 0]
= a. (b x c) + a. (b x a) + a.(c x a) + b. (b x c) + b. (b x a) + b . (c x a)
= a.(b x c) + b.(c x a)
= [a b c] + [a b c]
= [a b c] + [a b c] = 2 [a b c]