If y^2 - x^2 = 2xy, then (x+y)^2 =  Choose the correct choice from the following choices.
A) x^2 B) 3x^2 C) 4xy D) 2y^2 E) -y^2
Its B   y^2 -x^2 = 2xy   y^2 = 2xy + x^2   Add y^2 on both sides we get   y^2 +y^2 = x^2+2xy+y^2   2y^2 = (x+y)^2   Correct Option : 2y^2
<result>D</result>
If y^2 - x^2 = 2xy, then (x+y)^2 =