\documentclass{beamer}
\usepackage[accumulated]{beamerseminar}
\usepackage{amsmath}
%\mathindent=0pt

\begin{document}

\begin{frame}

\begin{flalign*}
A_1x & \leq b_1,&\\
A_2x & \geq b_2,&\\
x & \geq 0,&
\end{flalign*}

\end{frame}

\end{document}