2(a2+b2) =?
A
(a+b)2-2ab
B
(a+b)2+(a-b)2
C
(a-b)2-2ab
D
(a+b)2-4ab
Correct Answer: (a+b)2+(a-b)2
2(a^2 + b^2) = (a + b)^2 + (a - b)^2