Is a Matrix Invertible in Modular Arithmetic if det(A) and n are Coprime?

[nahuel_pelado]

This is the question: What must fulfill a matrix to be invertible in module Zn? Demonstrate. Z refers to integers.

I really appreciate that someone could help me with this because i couldn't find strong information about it.
I think that considering A as a matrix... the det(A) must be coprime with the module (n), so that gcd(det(A),n)=1 but I'm not sure about it.

In case that a matrix has inverse in module Zn, is correct to use this to verify?: A.A^-1 mod n = A^-1.A mod n = I ... I = identity matrix

 

[trambolin]

Hint : What is a unimodular matrix?

Another hint: A square polynomial matrix U in \mathbb{R}^{n\times n}[x] is unimodular if the determinant \det U \neq 0 is a constant. The inverse of a unimodular polynomial matrix is again a polynomial matrix.

 

[Hurkyl]

Why does a real matrix with invertible determinant have to have an inverse?