Упростите выражение. 1/x-y * 1/x-y * ( x/y - y/x)

Question

Упростите выражение.

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

Answer 1

1/(x-y)*1/(x-y)*(x/y-y/x) 

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