Consider a unity negative feedback system with Gc(s) = K and G(s) = s2 - s +

Question:

Consider a unity negative feedback system with
Gc(s) = K and G(s) = s2 - s + 2 / s2 + 2s + 1.
Develop an m-file to compute the roots of the closed-loop transfer function characteristic polynomial for K = 1, 2, and 5. For which values of K is the closed-loop system stable?