3 of the 4 expressions (1), (2), (3) & (4) given below are exactly equal . Which of the expression is not equal to the other four expressions?	Pick one:  A) (A – B)2 + 9AB  B) (A – B)2 + 4AJ  C) (A – B)2 + 4AB  D) (A – B)2 + 2AB  E) (A – B)2 + 1AB
Explanation:   1) (A + B)2 – 4AB = A2 + 2AB + B2 - 4AB = A2 + B2 - 2AB   2) (A – B)2 + 4AB = A2 – 2AB + B2 + 4AB = A2+ B2 + 2= 
<gadget id="calculator">+ 2</gadget>
<output>2</output>
A2 + B2 - 2AB   4) A2 – B2 + 2B(B – A)= A2 – B2 + 2B2 – 2AB = A2 + B2 – 2AB   Therefore, (1) = (3) = (4) ≠ (2)   Therefore, expression (2) is wrong   ANSWER:(A – B)2 + 4AB
<result>C</result>
3 of the 4 expressions (1), (2), (3) & (4) given below are exactly equal . Which of the expression is not equal to the other four expressions?