[tex]\bf \begin{array}{lllll}
&x_1&y_1\\
% (a,b)
&({{ 1}}\quad ,&{{ -2}})\quad
\end{array}
\\\\\\
% slope = m
slope = {{ m}}= \cfrac{rise}{run} \implies 0
\\\\\\
% point-slope intercept
\stackrel{\textit{point-slope form}}{y-{{ y_1}}={{ m}}(x-{{ x_1}})}\implies y-(-2)=0(x-1)
\\\\\\
y+2=0\implies y=-2[/tex]
