Ответы и объяснения

2013-05-21T18:37:22+00:00

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