Х+у-х+у
=-------------×(х-у)(х+у)/у^2=
(х-у)(х+у)
2у
=-------=2/у
у^2
₩₩₩₩₩₩₩
=(1/х^2+1/у^2 +
1×2(х+у)
+--------------)×х^2у^2/х^2-у^2=
(х+у)×ху
=(1/х^2+1/у^2+2/ху)×х^2у^2/х^2-у^2=
у^2+х^2+2ху
=---------------------- ×х^2у^2/(х-у)(х+у)=
х^2у^2
(х+у)^2
=-----------------=(х+у)/(х-у)
(х-у)(х+у)