ИС
Ириска Сладенькая
x^3+y^3/x+y=(х+у) (х²-ху+у²)/(х+у) =х²-ху+у²
x^3+y^3/x+y :(x^2-y^2) + 2y/x+y -xy/x^2-y^2 =
= (х²-ху+y²)/[(х-у) (х+у) ] + 2у·(х-у) /[(х-у) (х+у) ] - ху/[(х-у) (х+у)] =
=(х²-ху+у²+2ху-2у²-ху) /(х²-у²)=
= (х²-у²)/(х²-у²)=
=1