Question 1046198
{{{((1/xy)-1)/((1/x^2)-(y/x))}}}


Multiply the entire fraction by  {{{(x^2y)/(x^2y)}}} and simplify.

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{{{highlight((x-x^2y)/(y-xy^2))}}}


{{{highlight((x(1-xy))/(y(1-xy)))}}},
which is almost the same as  {{{x/y}}}, but does not truely mnean the same.  In the case that xy=1, the expression will be undefined, except in the "simplifed" form, but {{{x/y}}} is NOT identical with  {{{(x(1-xy))/(y(1-xy))}}}.