Simplify x4−y4x2+y2\frac{x^4-y^4}{x^2+y^2}x2+y2x4−y4.
x2−y2x^2-y^2x2−y2
x2+y2x^2+y^2x2+y2
x−yx-yx−y
x+yx+yx+y