Solution
= Solution
The class
$$
X=-1
$$
satisfies $X^3=-1$ for every prime. Thus a solution exists for every odd prime $p$, regardless of its residue class modulo $3$.
= Solution
The class
$$
X=-1
$$
satisfies $X^3=-1$ for every prime. Thus a solution exists for every odd prime $p$, regardless of its residue class modulo $3$.