A second-order linear time-invariant system is described by the following state equations
$$\frac{d}{dt}x_1(t)+2x_1(t)=3u(t)$$
$$\frac{d}{dt}x_2(t)+x_2(t)=u(t)$$
where $x_1(t)$ and $x_2(t)$ are the two state variables and $u(t)$ denotes the input. If the output $c(t)=x_1(t)$, then the system is
- controllable but not observable
- observable but not controllable
- both controllable and observable
- neither controllable nor observable