The characteristic equation of the control system is s^5+15s^4+85s^3+225s^2+274s+120=0 . What are the number of roots of the equation which lie to the left of the line s+1 = 0?
(a) 2
(b) 3
(c) 4
(d) 5
I had been asked this question during an internship interview.
Origin of the question is Compensation Techniques topic in division Digital Control Systems of Control Systems