Question

The range of K for which all the roots of the equation $s^3+3s^2+2s+K=0$ are in the left half of the complex s-plane is

• A. 0 < K < 6
• B. 0 < K < 16
• C. 6 < K < 36
• D. 6 < K < 16

Answer 1

The correct option is A 0 < K < 6

From the given equation,

$s^3+3s^2+2s+K=0$

Using Routh's criterion, we get

K < 6 and K > 0 or 0 < K < 6