Does the folloowing set of polynomials span $\displaystyle P_2$?

$\displaystyle {t^2+2t-1, t^2-1}$

When I formed the coefficient matrix I got

$\displaystyle

\left[ {\begin{array}{ccc}

1 & 1 & 0 \\

2 & 0 & 0 \\

-1 & 0 & 0 \\

\end{array} } \right]

$

but the answer key had

$\displaystyle

\left[ {\begin{array}{cc}

1 & 1 \\

2 & 0 \\

-1 & 0 \\

\end{array} } \right]

$

Is one right/wrong or better?