Simplify: x−2−y−2x−1+y−1\dfrac{x^{-2} - y^{-2}}{x^{-1} + y^{-1}}x−1+y−1x−2−y−2
y−xxy\dfrac{y-x}{xy}xyy−x
x−yxy\dfrac{x-y}{xy}xyx−y
1x+1y\dfrac{1}{x} + \dfrac{1}{y}x1+y1
x+yxy\dfrac{x+y}{xy}xyx+y