SamverkanLinalgLIU

1. \displaystyle \begin{pmatrix}1&0\\0&{-1}\end{pmatrix}.

2. \displaystyle \frac{1}{2}\begin{pmatrix}1&{-1}\\{-1}&1\end{pmatrix}.

3. \displaystyle \begin{pmatrix}0&{-1}\\{-1}&0\end{pmatrix}

4. \displaystyle \frac{1}{25}\begin{pmatrix}9&{-12}\\{-12}&{16}\end{pmatrix}.