Inverse Laplace transform $\frac{s^{2}}{(s^{2} + 100)^{2}}$

Question

How to find inverse Laplace transform of $F(s) = \frac{s^{2}}{(s^{2} + 100)^{2}}$? I do not ask for a solution, I simply can not understand which method I can use to solve it. I tried partial fraction, but they do not work, I tried convolutions, but it seems impossible ...

Answer 1

(This should probably be a comment, but I my reputation makes me untrustworthy)

Partial fractions with complex factors ought to work, i.e. $(s^2+100)^2=(s+10i)^2(s-10i)^2$.