How to cross out few entries in table?

Question

I want to create a table similar to one shown below. I know how to create a table using tabular environment but I don't know

1. how to put these red horizontal lines that eliminate few of the entries in this table.
2. how to group these lines with table so that incase size of table needs some adjustment, the lines also get adjusted automatically.

Answer 1

Since you seem to want to have shadows, it might be easier to draw the whole thing in TikZ.

\documentclass[tikz,border=3.14mm]{standalone}
\usetikzlibrary{calc,matrix,shadows.blur,decorations.pathreplacing}
\tikzset{shadowed/.style={decorate,decoration={
show path construction,
lineto code={
\draw[#1!50!gray,opacity=0.5] ([xshift=0.5ex,yshift=-0.25ex]\tikzinputsegmentfirst) -- ([xshift=0.5ex,yshift=-0.25ex]\tikzinputsegmentlast);
\draw[#1] (\tikzinputsegmentfirst) -- (\tikzinputsegmentlast);
}}}}
\begin{document}
\begin{tikzpicture}[buffy/.style={circle,draw,inner sep=3pt,fill=#1,blur shadow}]
\matrix[matrix of nodes,nodes={align=center,anchor=center},row sep=4pt] (mat)
 {  $x_1$ & $x_2$ & $x_3$\\
   |[buffy=blue]| & |[buffy=blue]| & |[buffy=blue]|\\
   |[buffy=blue]| & |[buffy=blue]| & |[buffy=gray]|\\
   |[buffy=blue]| & |[buffy=gray]| & |[buffy=blue]|\\
   |[buffy=blue]| & |[buffy=gray]| & |[buffy=gray]|\\     
   |[buffy=gray]| & |[buffy=blue]| & |[buffy=blue]|\\   
   |[buffy=gray]| & |[buffy=blue]| & |[buffy=gray]|\\   
   |[buffy=gray]| & |[buffy=gray]| & |[buffy=blue]|\\   
   |[buffy=gray]| & |[buffy=gray]| & |[buffy=gray]|\\
    };
\path ($(mat-1-1.north east)!0.5!(mat-1-2.north west)$) coordinate (auxL)
 ($(mat-1-2.north east)!0.5!(mat-1-3.north west)$) coordinate (auxR)
 ($(mat-1-1.south west)!0.5!(mat-2-1.north west)$) coordinate (auxT);
\draw[shadowed=black] (auxL |- mat.north) -- (auxL |- mat.south)
(auxR |- mat.north) -- (auxR |- mat.south)
(auxT -| mat.west) -- (auxT -| mat.east);
\begin{scope}[thick]
\foreach \X in {5,7,8,9}
{\draw[shadowed=red] (mat-\X-1.center -| mat.west) -- (mat-\X-3.center -| mat.east);}
\end{scope}
\end{tikzpicture}
\end{document}