A problem with the Legendre/Jacobi symbols: $\sum_{n=1}^{p}\left(\frac{an+b}{p}\right)=0$ [duplicate]
Solution 1:
Hint: As $n$ ranges from $1$ to $p$, $an+b$ ranges over all residue classes modulo $p$.
Hint: As $n$ ranges from $1$ to $p$, $an+b$ ranges over all residue classes modulo $p$.