1. \displaystyle A_{\boldsymbol{f}}=\begin{pmatrix}1&0\\0&{-1}\end{pmatrix}
2. \displaystyle A_{\boldsymbol{e}}=TA_{\boldsymbol{f}}T^{-1}=\frac{1}{5}\begin{pmatrix}3&{-4}\\{-4}&{-3}\end{pmatrix}.
