"note that "y-4=0" can be expressed as "y=4note that y−4=0 can be expressed as y=4
"This is a horizontal line parallel to the x-axis passing "This is a horizontal line parallel to the x-axis passing
"through all points in the plane with a y-coordinate "=4through all points in the plane with a y-coordinate =4
"A line perpendicular to "y=4" must therefore be a "A line perpendicular to y=4 must therefore be a
"vertical line parallel to the y-axis"vertical line parallel to the y-axis
"such a line has equation "x=c" where c is the value"such a line has equation x=c where c is the value
"of the x-coordinate the line passes through"of the x-coordinate the line passes through
"here the line passes through "(-1,6)here the line passes through (−1,6)
"the equation of the perpendicular line is therefore"the equation of the perpendicular line is therefore
color(red)(bar(ul(|color(white)(2/2)color(black)(x=-1)color(white)(2/2)|)))
graph{(y-0.001x-4)(y-1000x-1000)=0 [-10, 10, -5, 5]}
