Solving linear DE systems using fundamental matrix

[member 731016]

Homework Statement

Please see below

Relevant Equations

Please see below

For this problem,

I am confused by the term below. I get all their terms, expect replacing the highlighted term by $e^{3t}$, does someone please know whether this is yet another typo?

Thanks!

 

[Orodruin]

Obviously a typo. And not the first one …

 

[member 731016]

Obviously a typo. And not the first one …

Thank you for your reply @Orodruin! Do you also please know why they include a comma in the matrix fundamental matrix? It seems a strange use of notation to mean.

Thanks!