像这样吗?
\documentclass{article} % or some other suitable document class
\usepackage{amsmath} % for 'alignat' environment
\begin{document}
\begin{alignat}{3}
0x_1& && &&= 0 \nonumber \\
-2x_1&-8x_2&&+2x_3 &&= 0 \\
x_1&-3x_2&&-\phantom{2}x_3&&= 0
\end{alignat}
\end{document}