Question 630316
{{{ y = -1 }}} is a line through the point ( 0,-1 )
and is parallel to the x-axis
---------
Any line perpendicular to this line has to be
parallel to the y-axis, so it has an infinite slope
---------
Since it goes through (1,6), every point on this line
has the same x-coordinate, and looks like (1,y)
where {{{y}}} can be any value.
---------
So {{{ x = 1 }}} describes this line