1. The problem statement, all variables and given/known data The controller K(s) = Kp, determine the range of Kp over which the closed loop system is stable. 2. Relevant equations I found the transfer function of system = Y(s)/V(s)=Kp/(1.5s^2 + 2.5s - 1 + Kp) 3. The attempt at a solution So i know (1.5s^2 + 2.5s - 1 + Kp) is the characteristic equation is been a while since ive done these i think i remember that all roots of the polynomial for a stable system must be negative real parts and i know its probably obvious but i just cant remember how to find the range of Kp. Thanks!