Question

For all real numbers a and b, 2a • b = a2 + b2 True Or False ! Explain

Answer 1

This is true only if one of a or b is negative
(a-b)^2 is 0
a^2+b^2-2ab=0
a^2+b^2=2ab

(A-b)^2 is 0
if a-b=0

Answer 2

This may be equal with this formula of 

(a-b)^2 = a^2 -2ab +b^2