Adc motor position control system can be modeled as: (d2 + 4d + k) y(t) = k x(t) where k is a design parameter (the gain constant), y(t) is the position, x(t) is the input

(a) specify the value of k at which the system is critically damped.
(b) for what values of k is the system underdamped?
(c) for what values of k is the system overdamped?