ENGR201 Laplace deck example, partial fractions with a repeated poleTutorialOld spec ENGR2012:28 min

ENGR201 (old spec) Laplace transforms deck, partial fractions case 2 (page 37)

Find L−1[X(s)]\mathcal{L}^{-1}[X(s)] for X(s)=s2+3s+4(s+1)3X(s) = \frac{s^2 + 3s + 4}{(s + 1)^3} and evaluate the result at t=1t = 1.

Formulas you may need
  • Repeated factor (s+1)3(s + 1)^3: terms As+1+B(s+1)2+C(s+1)3\dfrac{A}{s + 1} + \dfrac{B}{(s + 1)^2} + \dfrac{C}{(s + 1)^3} (learn this)
  • L−1[n!(s−a)n+1]=tneat\mathcal{L}^{-1}\left[\dfrac{n!}{(s - a)^{n+1}}\right] = t^ne^{at} (learn this)