Ответы и объяснения

2012-05-01T09:21:51+00:00

(x/у - у/х)(х/у + у/х - 2)^-1 = (х^2 - y^2)(x^2 + y^2 - 2xy)^-1 = (x^2 - y^2)(1/(x^2 + y^2 - 2xy)) = (x^2 - y^2)/(x^2 + y^2 - 2xy) = ((x-y)(x+y))/(x^2 - 2xy +y^2) =  ((x-y)(x+y))/ (x-y)^2 = (x + y)/ (x - y)