\documentclass[a4paper,11pt]{report}
\usepackage[latin1]{inputenc}
\usepackage[italian]{babel}
\usepackage{graphicx}

\newtheorem{prop}{Proposizione}
\newtheorem{defin}{Definizione}
\newtheorem{oss}{Osservazione}
\newtheorem{ese}{Esempio}


\begin{document}

\begin{equation}
\label{ptap} \left(
\begin{array}{ccc}
x' & y' & 1
\end{array}
\right) \left(
\begin{tabular}{ccc}
        & \multicolumn{2}{c}{$\gamma$}\\
\raisebox{1.5ex}[0cm][0cm]{$P$}
         &$\delta$                   \\
0\quad\,0&1                  \\
\end{tabular}
 \right)^t A
\left(
\begin{tabular}{ccc}
        & \multicolumn{2}{c}{$\gamma$}\\
\raisebox{1.5ex}[0cm][0cm]{$P$}
         &$\delta$                   \\
0\quad\,0&1                  \\
\end{tabular}
 \right)
 \left(
\begin{array}{c}
x'\\y'\\1
\end{array}
\right)=0.
\end{equation}
\end{document}
