Coordinate planes and functions
The coordinate plane is a two-dimension surface formed by two number lines. One number line is horizontal and is called the x-axis. The other number line is vertical number line and is called the y-axis. The two axes meet at a point called the origin.1
Essentially, coordinate planes (aka number planes) are used to visualise elements (placed using coordinates). Equations, functions, and data sets are frequently represented via coordinate planes.
But what is a function?
A function is a set of instructions for calculating a single value (or performing an action in the case of programming). Take, for instance, the equation y=(x*2): in order to determine the y value, AKA the range, (which could be represented via any other character), you take your x value, AKA the domain and multiply it by 2.
Example via function table
| x | 0 | 1 | 2 | 3 | 4 |
| y=(x*2) | 0 | 2 | 4 | 6 | 8 |
What about the funny looking functions that don't look like the example at all?
Ah yes, the dreaded ƒ(x)=y (read "a function of x equals y"). It really is a beast... or is it?
The ƒ signals the name of a function, x denotes input, and y denotes output. Just like before, these variables can be represented with different letters, but these are used as the default. Example: ƒ(x)=x*2. Once more, you can replace the x with any value and you'll get the result the same way you get results for y=x*2.
I get it now. As you were saying?
There are many applications for coordinate planes- those will be covered later on demand. The purpose of this journal entry was to explain what coordinate planes and functions are.
Sources
1. Points on the coordinate plane examples. Khan Academy; [accessed 2026 July 30]. https://www.khanacademy.org/math/cc-sixth-grade-math/x0267d782:coordinate-plane/cc-6th-coordinate-plane/v/the-coordinate-plane
Further studying
1. Algebra Basics: What Are Functions? -Math Antics (on Youtube)