Solution 4.6.2.2 The characteristic polynomial is p(s)=s 6 +5s 5 +6s 4 +10s 3 +0s 2 +4s +1: The initial Routh table is s 6 1 6 0 1 0 s 5 5 10 4 0 0 s 4 b 1 b 2 b 3 0 0 s 3 c 1 c 2 c 3 0 0 s 2 d 1 d 2 d 3 0 0 s 1 e 1 e 2 e 3 0 0 s 0 f 1 f 2 f 3 0 0 . Then b 1 = ;Det " 1 6 5 10 # 5 = ;(10;30) 5 =4;; b 2 = ;Det " 1 0 5 4 # 5 = ;(4;0) 5 = ;4=5 b 3 = ;Det " 1 1 5 0 # 5 = ;(0;5) 5 =1 The partially completed Routh table is then s 6 1 6 0 1 0 s 5 5 10 4 0 0 s 4 4 ;4=5 1 0 0 s 3 c 1 c 2 c 3 0 0 s 2 d 1 d 2 d 3 0 0 s 1 e 1 e 2 e 3 0 0 s 0 f 1 f 2 f 3 0 0 . 1 c 1 = ;Det " 5 10 4 ;4=5 # 4 = ;(;4;40) 4 = 11 c 2 = ;Det " 5 4 4 1 # 5 = ;(5;16) 5 = 16=5 c 3 = ;Det " 5 0 4 0 # 5 = ;(0;0) 4 = 0 The Routh table is now: s 6 1 6 0 1 0 s 5 5 10 4 0 0 s 4 4 ;4=5 1 0 0 s 3 11 16=5 0 0 0 s 2 d 1 d 2 d 3 0 0 s 1 e 1 e 2 e 3 0 0 s 0 f 1 f 2 f 3 0 0 . d 1 = ;Det " 4 ;4=5 11 16=5 # 11 = ;(64=5+44=5) 11 = ;108=55 2 d 2 = ;Det " 4 1 11 0 # 11 = 1 d 3 = ;Det " 4 0 11 0 # 11 = 0 The partially complete Routh arrayisnow s 6 1 6 0 1 0 s 5 5 10 4 0 0 s 4 4 ;4=5 1 0 0 s 3 11 16=5 0 0 0 s 2 ;108=55 1 0 0 0 s 1 e 1 e 2 e 3 0 0 s 0 f 1 f 2 f 3 0 0 . e 1 = ;Det " 11 16=5 ;108=55 1 # ;108=55 = ;(11 + 1728=275)=(;108=55) = 4753=540 e 2 = ;Det " 11 0 ;108=55 0 # ;108=55 = 0 e 3 = ;Det " 11 0 ;1;8=55 0 # ;108=55 = 0 The partially nished Routh table is now 3 s 6 1 6 0 1 0 s 5 5 10 4 0 0 s 4 4 ;4=5 1 0 0 s 3 11 16=5 0 0 0 s 2 ;108=55 1 0 0 0 s 1 4753=540 0 0 0 0 s 0 f 1 f 2 f 3 0 0 . f 1 = ;Det " ;108=55 1 4753=540 0 # 4753=540 = ; ;4753=540 4753=540 = 1 f 2 = ;Det " ;108=55 0 4753=540 0 # 4753=540 = 0 f 3 = ;Det " ;108=55 0 4753=540 0 # 4753=540 = 0 The nal Routh table is s 6 1 6 0 1 0 s 5 5 10 4 0 0 s 4 4 ;4=5 1 0 0 s 3 11 16=5 0 0 0 s 2 ;108=55 1 0 0 0 s 1 4753=540 0 0 0 0 s 0 1 0 0 0 0 . There are two sign changes, positivetonegativeand negativetopostiveas wegofromrow4torow5t0row6.Thus there are tworoots in the right half plane. This is veri ed by the MATLAB dialogure: 4 EDU>p = [1 5610041] p= 1 5 6 10 0 4 1 EDU>roots(p) ans = -4.1474 -0.5655+ 1.4611i -0.5655- 1.4611i 0.2515+ 0.6114i 0.2515- 0.6114i -0.2248 EDU> It is clear that a program likeMATLAB obviates muchofthe value of the Routh criterion. 5