Consider a linear time-invariant system whose input $\text{r(t)}$ and output $\text{y(t)}$ are related by the following differential equation:
$$\frac{d^{2}y\left ( t \right )}{dt^{2}}+4y\left ( t \right )=6r\left ( t \right )$$
The poles of this system are at
- $+2j,-2j$
- $+2,-2$
- $+4,-4$
- $+4j,-4j$