The state variable equations of a system are:
$\begin{array}{l} 1. \; x_{1}=-3 x_{1}-x_{2}+u \\ 2. \; x_{2}=2 x_{1} \\ \quad y=x_{1}+u \end{array}$
The system is
- controllable but not observable
- observable but not controllable
- neither controllable nor observable
- controllable and observable