Finding a subset of S that is a basis for W.

Let W be the subspace of M_2x2 (R) consisting of the symmetric 2x2 matrices. The set

S= {$\displaystyle [

\begin{pmatrix}

0 & -1 \\

-1 & 1 \\

\end{pmatrix} \]$, $\displaystyle [

\begin{pmatrix}

1 & 2 \\

2 & 3 \\

\end{pmatrix} \]$$\displaystyle [

\begin{pmatrix}

2 & 1 \\

1 & 9 \\

\end{pmatrix} \]$

$\displaystyle [

\begin{pmatrix}

1 & -2 \\

-2 & 4 \\

\end{pmatrix} \]$

$\displaystyle [

\begin{pmatrix}

-1 & 2 \\

2 & -1 \\

\end{pmatrix} \]$}

generates W. Find a subset of S that is a basis for W.

(I'm not sure what all the (0)'s are next to my matrices but they aren't supposed to be there its only supposed to be the 5 matrices)