Question

The characteristic equation of a control system is given by s^5+s^4+2s^3+2s^2+4s+6=0. The number of the roots of the equation which lie on the right half of s-plane:

(a) 0

(b) 1

(c) 2

(d) 3

This question was addressed to me in final exam.

My query is from Compensation Techniques in section Digital Control Systems of Control Systems

Answer 1

Correct answer is (c) 2

For explanation: The solution is obtained by using the Routh-Hurwitz table in which with the conventional method the number of sign changes are seen in the first row of the table and number of sign changes is equal to the number of the roots on the right half of s plane.