Question 179
Does there exist a function $f(x): \mathbb{R} \to \mathbb{R}$ satisfying the equality
$$
f(|x|) + |f(x)| = x
$$
for all real numbers $x$?
$$
f(|x|) + |f(x)| = x
$$
for all real numbers $x$?
MathNet 2019-part-01 — 184 problems (EN–VI) Question 179
Math Olympiad Vault · MathNet 2019-part-01 — 184 problems (EN–VI)