- #1

- 5

- 0

## Homework Statement

Let n be a whole number of the form ##n=x^2+1## with ##x \in Z##, and p an odd prime that divides n.

Proof: ##p \equiv 1 \mod 4##.

## Homework Equations

## The Attempt at a Solution

The only relevant case is if p=3 mod 4.

If I try to calculate mod 3, or mod 4, or mod p, I'm not getting anywhere.