\documentclass{standalone}
\usepackage{booktabs}
\usepackage{graphicx}
\usepackage{multirow}
\usepackage{amssymb}
\usepackage{amsmath}
\usepackage{pifont}
\usepackage{xcolor}
\usepackage[margin=1in]{geometry}
\begin{document}
% created using textables on Wed Mar 22 21:06:02 2023
\begin{tabular}{lcc}
\toprule 
\midrule 
{\color{red} hello} & \multicolumn{2}{c}{{\color{blue} world}} \\
 \cmidrule(lr){1-1} \cmidrule(lr){2-3} 
$\alpha$ & $\frac{1}{2}$ & $\sqrt{\frac{2}{3}}$ \\
\midrule 
\bottomrule 
\end{tabular}
\end{document}
