I've found this sheet online and I need some help with it.

It asks to use Inverse Laplace Transforms to solve L^-1{(s^2 + 1)^(1/2)} by using a few different methods different methods.
> Applying a convolution theorem to (s + i)^-1/2(s - i)^-1/2
> Expanding certain terms in binomial series and taking Laplace transforms term by term
> Using Complex Inversion Theorem.

Now, I can understand the middle step, but I'm having trouble with the first and third? I'm not sure how I even start. Can anyone help?