Question 314504
{{{((1/y^2)-(1/x^2))/ ((1/y^2) + (1/x^2))=( x^2y^2*(1/y^2)-x^2y^2*(1/x^2))/ (x^2y^2*(1/y^2) + x^2y^2*(1/x^2))}}}
{{{((1/y^2)-(1/x^2))/ ((1/y^2) + (1/x^2))=( x^2-y^2)/ (x^2 + y^2)}}}
{{{((1/y^2)-(1/x^2))/ ((1/y^2) + (1/x^2))=((x+y)(x-y))/ (x^2 + y^2)}}}