Why do we use letters like x and y to represent numbers in algebra?
In: Mathematics
We want to describe the math as clearly as possible, right? So we need to use symbols that people aren’t going to confuse with math symbols. We also need a lot of them! So what are a bunch of symbols that everyone in Europe was familiar with? The alphabet! They also are very simple and quick to write. Bonus points, we can assign letters that make sense with the quantities we are using so they are easy to remember. Like for length, width, and height, we can use L, W, and H.
There are other reasons it persists, but that’s the core. We try not to use e thanks to Euler’s constant using that letter, but otherwise we get so many symbols to use. By my count, we get about 40 easily distinguishable symbols with lowercase and uppercase letters.
If you do math within a given specialty, you might find they prefer particular symbols instead of the alphabet. Like we use capital theta (a Greek letter) to show an angle. This is a tradition from when the Greeks did the same, and now most mathematicians know that it means angle. It seems silly, but since everyone knows what it means, it makes it a good symbol for something that shows up a LOT. Electrical formulas sometimes use capital omega for resistance, because the resistance unit (Ohm) has omega as its symbol (though mostly R is used instead, R for resistance!).
Why do sometimes use letters and sometimes other symbols? Letters are great when you tell someone that “y means this”, they know the letter and only need to remember the connection. Other symbols are used for things where everyone doing that math would know the symbol already, because it’s really important for that math.
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