Ok thanks for the help!
I am doing it now with partial fractions to confirm.
I have never used MathCAD, is there a way to put the original differential equation: d³/dt³ (y) + d²/dt² (y) + dy/dt + y = d²/dt² (u) + du/dt + u, into it and have it solve that way?
Is it a lot of trouble to do this?
Thanks for your time, this is a great help.
Edit:
Ok, partial fractions definitely does not work, because of the combination of an (s) and (s^2 +1) in the denominator.