Question

((x/y)-(y/x))((x/y)+(y/x)-2)^-1

Answer 1

$( \frac{x}{y} - \frac{y}{x})( \frac{x}{y}+ \frac{y}{x}-2)^{-1}= \\ = ( \frac{x}{y} - \frac{y}{x})( \frac{x^2+y^2-2xy}{xy})^{-1} = \\ = \frac{x^2-y^2}{xy} \frac{xy}{(x-y)^2}= \frac{(x-y)(x+y)}{(x-y)^2}= \\ = \frac{x+y}{x-y}$