Question 127448
Remember that a line having a zero slope is a horizontal line!
If such a line passes through the point (1, -8), then its equation is y = -8.
Why? Because a horizontal line (m = 0) passing through the point (1, -8) is the locus of all points whose y-coordinate is -8, and it doesn't matter what the x-coordinate is.
If the equation of your line were x = -8, you would have a vertical and the slope of a vertical line is undefined.