Question Number 119800 by Ar Brandon last updated on 27/Oct/20
$$\mathrm{Examples}\:\mathrm{of}\:\mathrm{functions}\:\mathrm{such}\:\mathrm{that} \\ $$$${f}\left(\mathrm{x}+\mathrm{y}\right)={f}\left(\mathrm{x}\right)+{f}\left(\mathrm{y}\right)\:\mathrm{for}\:\mathrm{all}\:\mathrm{x},\mathrm{y}\in\mathbb{R} \\ $$
Commented by mr W last updated on 27/Oct/20
$${f}\left({x}\right)={ax} \\ $$
Commented by Ar Brandon last updated on 27/Oct/20
OK, thank you Sir.