The first two rows of Routh's tabulation of a third order

The first two rows of Routh's tabulation of a third order equation are as follows.
s³ 2 2
s³ 4 4

This means there are

1. two roots at s = ± j and one root in right half s-plane
2. two roots at s = ± j2 and one root in left half s-plane
3. two roots at s = ± j2 and one root in right half s-plane
4. two roots at s = ± j and one root in left half s-plane

Two roots at s = ±j and one in left halfs-plane

s³	2	2
s³	4	4

Characteristic equation is A(s) = 2s³ + 4s² + 2s + 4 = 0
⇒ s³ + 2s² + s + 2 = 0
⇒ (s + 2) (s² + 1) = 0
⇒ s = – 2, s = ± j