Qualifying Exam Question On Elementary Group Theory
Let $n$ be the order of $h$. Then $$x = h^n x h^{-n} = x^{10^n}$$
So $10^n \equiv 1 \mod{p}$. Now apply the fact that $\gcd(p-1, n) = 1$.
Let $n$ be the order of $h$. Then $$x = h^n x h^{-n} = x^{10^n}$$
So $10^n \equiv 1 \mod{p}$. Now apply the fact that $\gcd(p-1, n) = 1$.