Consider the feedback system shown in Figure DP7.14. The process transfer function is marginally stable. The controller is the proportional-derivative (PD) controller
![](https://test.transtutors.com/qimg/59633c71-459e-461a-a3fe-2f03de22c041.png)
(a) Determine the characteristic equation of the closed-loop system.
(b) Let τ = Kp/KD. Write the characteristic equation in the form
![](https://test.transtutors.com/qimg/565790e9-feab-426d-ad2c-2d0a2137ea78.png)
![](https://test.transtutors.com/qimg/58d40218-0445-41ff-9503-3168b2297018.png)
![](https://test.transtutors.com/qimg/00a0ac12-04f4-4c60-bce0-3ae4e2c0773f.png)
![](https://test.transtutors.com/qimg/e718175b-8019-454e-8e15-325255325d5e.png)