Question about proof

[koukou]

prove Byron's Conjecture. Define the set
Znx={k∈Zn but not including zero ：gcd(k; n) = 1}
(a) Prove that Znx is a group under multiplication (mod n).
(b) Prove that an element a∈Zn is invertible in Zn (with respect to multiplication (mod n)) if and only if a∈Znx

Znx x should be above n . i dont know how to type

[jbunniii]

What's the question?

[VeeEight]

Use the fact that you can write out ak + bn = 1 for some integers a,b to show the elements are invertible.

[g_edgar]

LaTeX: \mathbb{Z}_n^{\times} ... use the "Quote" button to see it.