If x ¤ y = (x + y)^2 - (x - y)^2. Then √11 ¤ √11 =  Choices:
A) 44  B) 5  C) 10  D) 15  E) 20

Rationale: x = √ 11 and y also = √ 11 applying the function ( √ 11 + √ 11 ) ^ 2 - ( √ 11 - √ 11 ) ^ 2 = ( 2 √ 11 ) ^ 2 - 0 = 4 x 11 = 44 . note : alternative approach is the entire function is represented as x ^ 2 - y ^ 2 = ( x + y ) ( x - y ) which can be simplified as ( x + y + x - y ) ( x + y - ( x - y ) ) = ( 2 x ) ( 2 y ) = 4 xy . substituting x = √ 11 and y = √ 11 you get the answer 44 . answer a
Answer: A