For s functions in a$)$ b$)$ and c$),$ i$)$ find roots of their denominator $($poles$)$ and

ii$)$ find f$($t$),$ i$.$e$.$ inverse Laplace transform, based on their poles and cases for

partial fraction expansion:

a$)()=+3$

$2+2+5,$ b$)()=4+1$

$2(+1)2$

c$)()=4+8$

$42+12+13$