Coordinates are written in pairs called the “coordinate pair” and in the following format (x, y). Here, the x represents the x-cordinate and the y represents the y coordinate.
Graphs parallel to the y-axis
Where x = c, a graph will be parallel to the y-axis and will cut the x-axis as the point (c, 0). For example: where x = -10, x = -3, x = 4, x = 9 the following graph represents this line. In these scenarios, y can be any number.
Point to note: In this scenario, the lines will always be vertical and parallel to the y axis.
Graphs parallel to the x-axis
Similar to x = c, where y = c, c can be any number which is parallel to the x-axis. For example, the graph below displays where y = 5, y = 3, y = -2 and y = -5
Point to note: the y = c graph will always be parallel to the x-axis and therefore be horizontal.
Plotting graphs of linear functions
When plotting the graphs of a linear function, the x-coordinate and the y-coordinate pair can be linked by a function. For example:
y = x – 2 can be represented using the following coordinate pairs:
(1, -1), (4, 2), (-2, -4), (0, -2)
To plot these coordinate pairs in a graph, a table of values will need to be constructed:
For the following function y = 2x + 5, the following table is used:
This is then used to plot its graph as shown below: