Determine the relative stability of the systems with the following characteristic equations (1) by shifting the axis in the s-plane and using the Routh-Hurwitz criterion, and (2) by determining the location of the complex roots in the s-plane:
(a) s3 + 3s2 + 4s + 2 = 0.
(b) s4 + 9s3 + 30s2 + 42s + 20 = 0.
(c) s3 + 19s2 + 110s + 200 = 0.