documentclass[11pt,a4paper,twoside]{book}

usepackage{multirow}

begin{document}

begin{table}[h!]
centering
begin{tabular}{c|c|cc|c}
    &    &  $x_1$ &  $x_2$

&multirow{6}{*}{The most negative among $x_{Bi}, i=1,ldots,4$
    is -2. So $x_3$ will leave the basis.$mbox{max}Bigg{frac{z_j}{a_{sj}}|a_{3j}<0Bigg}=mbox{max}Bigg{frac{3}{-2}, frac{1}{-3}Bigg}=-frac{1}{-3}$  . So $x_2$
is entered into the basis. The pivot element is -3.} \

cline{1-4}
$z$   &   0 &  3   &   1  &\
cline{1-4}
$x_1$ &  0  &  -1   &   0  &\
$x_2$ &  0  &   0   &   -1  &\
$x_3$ &  -2 &  -2   &  -3 & \
$x_4$ &  -1 &  -1   &   -1  &\
cline{1-4}

end{tabular}
caption{}
end{table}
end{document}