\documentclass[a4paper,12pt]{article}
\newcommand\ds{\displaystyle}
\begin{document}

\parindent=0pt

QUESTION

Find the inverse Laplace transform of the function
$\ds\frac{1}{s^2+4}$.

\bigskip

ANSWER

$\ds{\cal{L}}^{-1}\left\{\frac{1}{s^2+4}\right\}=
{\cal{L}}^{-1}\left\{\frac{\frac{1}{2}(2)}{s^2+2^2}\right\}=
\frac{1}{2}\sin(2t)$




\end{document}
