(i)  $p\left(s\right)=s^4+4s^2+8$

The given polynomial contain even function only

$\therefore{}p^{'}\left(s\right)=4s^3+8s$

Routh array :

$\left.\begin{array}{ ccccc} s^4 \\ s^3 \\ s^2 \\ s \\ s^0 \end{array}\right\vert{}\begin{array}{ ccccc} 1 & 4 & 8 \\ 4 & 8 & \\ 2 & 8 & \\ -8 & & \\ 8 & & \end{array}$ …