a. (15%) Determine for the range of real number & the feedback system is stable

(d) (10%) Choose, among the following types of control, ones that are likely to regulate the system output to a constant level 0.5 with zero steady state error (One or more answers may be correct. Answers without supporting explanation are not acceptable): (1) P control (ii) I control (iii) D control (iv) PID control (v) PD control (vi) PI control