we have 2 points, A(1,-1) and B(8,6). We have to calculate the slope
[tex]m=\frac{6-(-1)}{8-1}=\frac{7}{7}=1[/tex]so we have that the equation is
[tex]\begin{gathered} y-6=x-8 \\ y=x-8+6=x-2 \end{gathered}[/tex]so we get that first asnwer is:
[tex]y=x-2[/tex]TO know if it pass through the center, we have to replace y by 4 and x by 3
[tex]\begin{gathered} 4=3-2=1\rightarrow4=1,\text{ but} \\ 4\ne1 \end{gathered}[/tex]so the answer for the second question is no. when you replace y by 4 and x by 3 you get something that is a lie, so that point does not belong to the line.