Question Number 44812 by jasno91 last updated on 05/Oct/18
Commented by math khazana by abdo last updated on 05/Oct/18
$${x}^{\mathrm{2}} \:+{y}^{\mathrm{2}} =\left({x}+{y}\right)^{\mathrm{2}} −\mathrm{2}{xy}\:=\mathrm{12}^{\mathrm{2}} \:−\mathrm{28}\:=\mathrm{144}−\mathrm{28} \\ $$$$=\mathrm{116} \\ $$