Simplify:
(a +b + c)(a + b + c)
(a +b + c)(a + b + c)
=a (a + b - c) + b( a 9 b - c) + c(a + b - c)
= ( a x a) + ( a x b) - ( a x c) + ( b x a) + ( b x b) - ( b x c)
+ ( c x a) + ( c x b) - (c x c)
= a2 + ab - ac + ab + b2 - bc + ac + bc - c2
= a2 +2ab + b2 - c2
= a2 + b2 - c2 + 2ab
Consider the special case of Identity (IV) with a = b, what do you get? Is it related to Identity (1)?
Consider, the special case of Identity (IV) with a = –c and b = –c. What do you get? Is it related to Identity (II)?