Question Number 10854 by Joel576 last updated on 27/Feb/17
$${f}\::\:\mathbb{R}\:\rightarrow\:\mathbb{R} \\ $$$${f}\left({x}\:.\:{f}\left({x}\right)\:+\:{f}\left({y}\right)\right)\:=\:\left({f}\left({x}\right)\right)^{\mathrm{2}} \:+\:{y}\:\:\:\:\:\:\:\:\:\:{x},{y}\:\in\:\mathbb{R} \\ $$$$ \\ $$$${f}\left({x}\right)\:=\:?? \\ $$
Answered by bahmanfeshki last updated on 02/Mar/17
$$ \\ $$$${f}\left({x}\right)={x} \\ $$