When solving many equations you usually stuff them in matrices and solve them using Gauss-Jordan elimination. Where I come from, we write it like this and this is what should appear in my document:

The gray parts of image are there for clarity and are not part of what I need. I just need (n+1) x n matrix with separation line. I will also need to display multiple of the matrices next to each other to show the GEM process:

How can I do it?

gauss, there's a way for using square brackets. Just do\begin{gmatrix}[b]instead of\begin{gmatrix}[p]– egreg Apr 25 '15 at 16:45