If $P=\frac{x^3+y^3}{(x-y)^2+3 x y}, Q=\frac{(x+y)^2-3 x y}{x^3-y^3}$ and $R=\frac{(x+y)^2+(x-y)^2}{x^2-y^2}$, then what is the value of $(P \div Q) \times R$ ?

2(x2 + y2) x2 + y2 4xy 2xy

2(x2 + y2)