4. Given the unity-feedback system of the figure below with 84 G(s) — s(s7 + Ss6 + 12s5 + 25s4 + 45.23 + SOs2 + 82s + 60) Use the Routh table to determine the following: a) How many poles of the closed-loop transfer function lie in the right half-plane. b) How many poles of the closed-loop transfer function lie in the left half-plane. c) How many poles of the closed-loop transfer function lie in the fa) axis d) Is this system stable? Circle one: Yes R(s) 1 + E(s) G(s) C(s)