How to use systeme to write a system of equations with subscripts in the coefficients

I am trying to type this system of equations:

I tried

\documentclass[12pt,a4paper]{article}
\usepackage{amsmath}
\begin{document}
$$\begin{cases} a_1 x+b_1 y+c_1 z=d_1, \\ a_2 x+b_2 y+c_2 z=d_2, \\ a_3 x+b_3 y+c_3 z=d_3. \end{cases}$$
\end{document}


With systeme package, I tried

\documentclass{article}
\usepackage{systeme}
\begin{document}
\systeme[xyz]{
a_1 x+b_1 y+c_1 z=d_1,
a_2 x+b_2 y+c_2 z=d_2,
a_3 x+b_3 y+c_3 z=d_3}
\end{document}


How can I use system package to get the result?

• Sep 23 at 7:28

You decide if it's worth the pain:

\documentclass[12pt,a4paper]{article}
\usepackage{amsmath,systeme}

\begin{document}

$$\syssubstitute{% {A}{a_1}{B}{b_1}{C}{c_1}{D}{d_1}% {E}{a_2}{F}{b_2}{G}{c_2}{H}{d_2}% {I}{a_3}{J}{b_3}{K}{c_3}{L}{d_3}% } \systeme[xyz]{ Ax + By + Cz = D, Ex + Fy + Gz = H, Ix + Jy + Kz = L }$$

\end{document}


Alternative, with comparison:

\documentclass[12pt,a4paper]{article}
\usepackage{amsmath,systeme,array}

\begin{document}

$$\left\{ \renewcommand{\arraystretch}{1.2} \setlength{\arraycolsep}{0pt} \begin{array}{ *{3}{c >{{}}c<{{}}}c } a_1x &+& b_1y &+& c_1z &=& d_1 \\ a_2x &+& b_2y &+& c_2z &=& d_2 \\ a_3x &+& b_3y &+& c_3z &=& d_3 \end{array} \right.$$

$$\syssubstitute{% {A}{a_1}{B}{b_1}{C}{c_1}{D}{d_1}% {E}{a_2}{F}{b_2}{G}{c_2}{H}{d_2}% {I}{a_3}{J}{b_3}{K}{c_3}{L}{d_3}% } \systeme[xyz]{ Ax + By + Cz = D, Ex + Fy + Gz = H, Ix + Jy + Kz = L }$$

\end{document}