\documentclass[12pt]{article}
\usepackage{amssymb,amsmath,amscd,concmath,amsfonts}
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\begin{document}
\begin{equation*}
H(s) = \frac{1}{s (s + 1)} \qquad
H(s) = \frac{1}{s^2 (s + 1)} \qquad
H(s) = \frac{1}{s^3 (s + 1)} \qquad
\end{equation*}
\end{document}