Simplify xx−y−yx+yxx+y+yx−y\frac{\frac{x}{x-y} - \frac{y}{x+y}}{\frac{x}{x+y} + \frac{y}{x-y}}x+yx+x−yyx−yx−x+yy
x2+y2x2−y2\frac{x^2+y^2}{x^2-y^2}x2−y2x2+y2
x2−y2x2+y2\frac{x^2-y^2}{x^2+y^2}x2+y2x2−y2
x2+y2x2+y2\frac{x^2+y^2}{x^2+y^2}x2+y2x2+y2
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