各位大侠帮助求拉氏反变换 (s^3)/((s^2+3*s+2)*s).

问题描述:

各位大侠帮助求拉氏反变换 (s^3)/((s^2+3*s+2)*s).

F(s)=(s^3)/((s^2+3*s+2)*s)
=1-(3s+2)/(s^2+3*s+2)
=1-(3s+2)/(s+1)(s+2)
=1+1/(s+1)-4/(s+2)
故f(t)=δ(t)+[e^(-t)-4*e^(-2t)]ε(t)