A vertical line is a line that goes straight up and down. It has no slope and is always perpendicular to the horizontal axis.
To graph a vertical line with equation x = k, simply draw a straight line that is perpendicular to the x-axis and passes through the point (k, 0).
1. Graph the vertical line with equation x = 3.
2. Determine if the following equations represent vertical lines: a) y = 2x + 1 b) x = -4