\[P\begin{Bmatrix}\alpha&\beta&\gamma&\\
a_{1}&b_{1}&c_{1}&z\\
a_{2}&b_{2}&c_{2}&\end{Bmatrix}=P\begin{Bmatrix}\widetilde{\alpha}&\widetilde{%
\beta}&\widetilde{\gamma}&\\
a_{1}&b_{1}&c_{1}&t\\
a_{2}&b_{2}&c_{2}&\end{Bmatrix}.\]