Electronics and Communication Engineering - Automatic Control Systems - Discussion


First column elements of Routh's tabulation are 3, 5, , 2. It means that there

[A]. is one root in left half s plane
[B]. are two roots in left half s plane
[C]. are two roots in right half s plane
[D]. is one root in right half s plane

Answer: Option C


Since there are two sign changes in the first column, hence two roots in right half plane.

Kishore said: (Nov 23, 2014)  
If there is negative sign in Routh's tabulation system became unstable. It means roots are at right half of s-plane. But here only one negative sign how two roots in right half s-plane?

Ta Meself said: (Feb 8, 2016)  
You have to look at sign CHANGES!

Swati said: (Jul 24, 2016)  
As root +5 changes to -3/4, here one sign change takes place and again from -3/4 to +1/2 second sign change occurs so there are two roots in the right half of s-plane.

Ajay said: (Jul 29, 2016)  
Well explained @Swati.

Shivani Aggarwal said: (Oct 27, 2016)  
Right, you are correct @@Swati.

Pkn said: (Dec 19, 2017)  
Correct @Swati.

Manjunath said: (Jan 16, 2018)  
Well explained @Swati.

Mukish Kumar said: (Nov 15, 2018)  
Great, very clear explanation. Thanks @Swati.

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