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\documentclass[12pt]{article}\usepackage[total={6.25in,10in},left=1.25in,top=0.5in,includehead,includefoot]{geometry}\usepackage{mathtools}\newcommand*{\1}{\hspace{1pt}}\newcommand*{\tsqrt}[1]{{\textstyle{\sqrt{#1}}}}\begin{document}Test :\begin{flalign}\mathrlap{\text{if $4 \, \omega_0^2 > \gamma^2$ :}} && \lambda &= \frac{1}{2} \1 \tsqrt{\displaystyle{4 \, \omega_0^2 - \gamma^2}}, & \\[12pt]\mathrlap{\text{if $4 \, \omega_0^2 < \gamma^2$ :}} && \kappa &= \frac{1}{2} \1 \tsqrt{\displaystyle{\gamma^2 - 4 \, \omega_0^2}}. &\end{flalign}\begin{equation}EQUATION\end{equation}\end{document}