A linear second order single input continuous time system is described by the following set of differential equations
$$ \begin{aligned} &x_1(t)=-2 x_1(t)+4 x_2(t) \\ &x_2(t)=2 x_1(t)-x_2(t)+u(t) \end{aligned} $$
Where $x_1(t)$ and $x_2(t)$ are the state variables and $u(t)$ is the control variable. The system is:
- controllable and stable
- controllable but unstable
- uncontrollable and unstable
- uncontrollable and stable