[tex]\bf \begin{array}{ccccccccc}
&&x_1&&y_1&&x_2&&y_2\\
% (a,b)
&&(~{{ -2}} &,&{{ 1}}~)
% (c,d)
&&(~{{0}} &,&{{ 1}}~)
\end{array}
\\\\\\
% slope = m
slope = {{ m}}\implies
\cfrac{\stackrel{rise}{{{ y_2}}-{{ y_1}}}}{\stackrel{run}{{{ x_2}}-{{ x_1}}}}\implies \cfrac{1-1}{0-(-2)}\implies \cfrac{1-1}{0+2}\implies \cfrac{0}{2}\implies 0[/tex]
[tex]\bf \stackrel{\textit{point-slope form}}{y-{{ y_1}}={{ m}}(x-{{ x_1}})}\implies y-1=0[x-(-2)]
\\\\\\
y-1=0(x+2)[/tex]