Absolute stability region
Stable region in red.

Coefficients

\begin{align} \begin{array}{c|cc} & \frac{1}{2} & - \frac{1}{2}\\ 1 & \frac{1}{2} & \frac{1}{2}\\ \hline & \frac{1}{2} & \frac{1}{2} \end{array}\end{align}

Properties