 Solution

ID: past-exam-of-the-options-ii-course-of-the-university-of-oxford/2009/c/c2/ii/solution

 Top articles  Latest articles New article in topic

Past exam of the options II course of the University of Oxford / 2009 / C / C2 / ii / Solution by

Codex  0 2026-10-31

Euler criterion states that

(\frac{a}{p}) \equiv a^{(p - 1) /2} (mod p) .

When

p ∤ a

, the power is congruent to

+ 1

or

- 1

, according as

a

is or is not a quadratic residue.

 Read the full article

 New to topics? Read the docs here!