Question 91
Find all complex numbers $a$ such that all coefficients of
$$
P(x) = (x - a)(x - a^2)(x - a^3)(x - a^4)
$$
are real numbers.
$$
P(x) = (x - a)(x - a^2)(x - a^3)(x - a^4)
$$
are real numbers.
MathNet 2019-part-02 — 184 problems (EN–VI) Question 91
Math Olympiad Vault · MathNet 2019-part-02 — 184 problems (EN–VI)