The characteristic equation of a feedback control system is s3+Ks2+9s+18. When the system is marginally stable, the frequency of the sustained oscillation:

The characteristic equation of a feedback control system is s3+Ks2+9s+

1.	The characteristic equation of a feedback control system is s3+Ks2+9s+18. When the system is marginally stable, the frequency of the sustained oscillation:
A.	1
B.	1.414
C.	1.732
D.	3
Answer» E.