# Math Help - Inverse Laplace Transform

1. ## Inverse Laplace Transform

I have no idea how to solve the problem with the inverse laplace transforms.

*Find the Inverse laplace transform of { 3/ (s + 4) }

I guessed that the answer, f(t) would be: 3 cos 2t

However it doesn't make sense because according to the table, -cos kt- is equal to F(s)=> s / (s^(2) + k^(2)).

In this case, s is not squared. I am not sure about k because I think it's not squared. If it is squared then k is equal to 2. That's how I got
3 cos 2t.

however if k is not squared then k is equal to 4. I am confused...

2. The inverse LaPlace of $\frac{3}{s+4}=3e^{-4t}$
$e^{-at}=\frac{1}{s+a}$