For Routh-Hurwitz problems, always inspect only the first column.
\[
\text{Number of sign changes}
=
\text{Number of right-half-plane poles}
\]
No sign change \(\Rightarrow\) Stable
One or more sign changes \(\Rightarrow\) Unstable
Entire row of zeros \(\Rightarrow\) Check for marginal stability.