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