Horizontal & Vertical Lines

Learn about graphs. In this second part introductory video we will look at the equation of horizontal lines and vertical lines. We will also have a quick look at two important diagonal lines. Vertical lines on a graph all have the same x-coordinate. This means they will have an x= equation. So x=2 and x=-3 are both vertical lines. The whole way up and down the line x=2, every single point has an x-coordinate of 2. Horizontal lines all have the same y-coordinate. This means that they will have a y = equation. So y = 2 and y = -3 are both horizontal lines. The whole way across the y = 2 line, every single point has a y-coordinate of 2. Diagonal lines starting from the bottom left and going up to the top right, cutting exactly through (-5, -5, (-3, -3) (0, 0) (1, 1) (3, 3) etc has the equation y = x. Whereas the diagonal line that starts in the top left and goes down to the bottom right, cutting exactly through (-5, 5) (-3, 3) (0, 0) (3, -3) (5, -5) etc has the equation y = -x or x = -y. The numbers are the same but the sign is different. Over the next 10 or so videos we will cover everything that you need to know about graphs, that you learn in school.