Prove that a2+b2+c2−ab−bc−ca is always non-negative for all values of a, b and c.

Prove that a2+b2+c2−ab−bc−ca is always non-negative for all val

1.	Prove that a2+b2+c2−ab−bc−ca is always non-negative for all values of a, b and c.
Answer» Prove that $a^{2} + b^{2} + c^{2} - a b - b c - c a$ is always non-negative for all values of a, b and c.