[texhax] Matrix aligment

[Andrei]

Hi,
I would like to make a matrix like this
-1  1  1
1  1  1

But the problem I like is to align to the right, because the sign with 
the number are always centered.
Im using:

\usepackage{amsmath}
\begin{gather}
   \begin{matrix}
      -1&1&1
       1&1&1
   \end{matrix}
\end{gather}

Thank you.