Chapter 6, Problem 15P

Given the unity feedback system of Figure P6.3 with

$G\left(s\right)=\frac{8}{s\left(s^6-2s^5-s^4+2s^3+4s^2-8s-4\right)}$

tell how many closed-loop poles are located in the right half-plane, in the left half-plane, and on the $j\omega -\text{axis}$ . [Section: 6.3]