# How to add horizontal line for subtraction in array

\documentclass{article}
\usepackage{amsmath}

\begin{document}
$k:\left\{ \begin{array}{cccccc}x & = & -3+3\lambda & \Big| & 4 & \Big| \\ y & = & 4-4\lambda & \Big| & -3 & \Big| \end{array} \right. \Rightarrow \left\{ \begin{array}{cccccc}4x & = & -12+12\lambda \\ -3y & = & -12+12\lambda \end{array} \right.$
\end{document}


I kind of want to have this:

What is the best way to get the subtraction line?

\documentclass{article}
\usepackage{amsmath}

\begin{document}

aaaaaa
\renewcommand\arraystretch{1.5} k:\Biggl\{ \begin{array}{@{}cccccc} x & = & -3+3\lambda \\ y & = & 4-4\lambda \end{array} \quad \Biggl|\begin{array}{@{}r@{}} 4\\ -3 \end{array} \Biggr| % \Rightarrow \Biggl\{ \begin{array}{@{}cccccc@{\qquad}l} 4x & = & -12+12\lambda \\ -3y & = & -12+12\lambda \\ \cline{1-3} 4x+3y&=&0&{}\Rightarrow x=-3/4 y\\ \noalign{\vspace{-1.5\normalbaselineskip}} \end{array}
\vspace{1.5\normalbaselineskip}
aaaa
\end{document}

• thank you very much! Can you also add the minus next to the line please? – user3024879 Nov 27 '14 at 15:01
• @user3024879 not so easily as it's a cline you could put &- in the row above or I suppose &\raisebox{-10pt}{$-$} to move it down again – David Carlisle Nov 27 '14 at 15:21