Consider:
\documentclass[12pt]{amsart}
\usepackage{tikz}
\begin{document}
\subsection {\bfseries Shembulli i dyte, Matrica.}
Konsiderojm matricen
\begin{equation*}
a = \begin{pmatrix}1 & 1\\ 0 & 1\end{pmatrix}
\end{equation*}.
Per ndonje e numer te tipit integjer n do te kemi formen e pergjitheshme:
\end{document}
This equation: {equation*} a = \begin{pmatrix}1 & 1\\ 0 & 1\end{pmatrix}\end{equation*}
You could use the smallmatrix environment for inline math use:
\documentclass[12pt]{amsart}
\begin{document}
\setcounter{section}{1} % just for this example
\subsection{Shembulli i dyte, Matrica.}
Konsiderojm matricen
$a = \bigl( \begin{smallmatrix}1 & 1\\ 0 & 1\end{smallmatrix}\bigr)$.
Per ndonje e numer te tipit integjer n do te kemi formen e pergjitheshme:
\end{document}
You can have a simpler way to type these matrices: use the psmallmatrix or psmallmatrix* command from mathtools. The starred version accepts as an optional argument the columns alignment ([r], [l] or the default [c]).
Similarly, you have the bsmallmatrix, Bsmallmatrix, vsmallmatrix or Vsmallmatrix environments.
\documentclass[12pt]{amsart}
\usepackage{mathtools}
\usepackage{nccmath}
\begin{document}
\subsection {\bfseries Shembulli i dyte, Matrica.}
Konsiderojm matricen
$ a = \begin{psmallmatrix}-1 & -1\\ 0 & 1\end{psmallmatrix} \neq \begin{psmallmatrix*}[r]-1 & -1\\ 0 & 1\end{psmallmatrix*} $.
Per ndonje e numer te tipit integjer n do te kemi formen e pergjitheshme:
\[ \begin{pmatrix*}[r]-1 & -1\\ 0 & 1\end{pmatrix*} \]%
\end{document}
Always use $ for inline:
$a = (\begin{matrix}1 & 1\\ 0 & 1\end{matrix})$
