Question

1/x-y * 1/x y * (x/y - y/x)

Answer 1

1/x-y * 1/x y * (x/y - y/x)=(xy(x-y))/ (xy(x-y))*((x^2-y^2)/ xy)= (xy*(x-y)*xy)/( xy(x-y)*(x-y)*(x+y)=xy/(x^2-y^2);