(s+3)/(s^2+2s+5) = (s+1)/{(s+1)^2+4} + 2/{(s+1)^2+4}
→ e^(-t)sin(2t)+e^(-2t)cos(2t)

1/(s^2(s+1)) = -1/s+1/s^2+1/(s+1)
→ -1+t+e^(-t)