Why X?

When we started learning Algebra, all of us were introduced to the idea that X = some unknown.

But did your teacher ever explain why “X”? 

Isn’t “A” a more logical choice, being the first letter of the alphabet. Or why not “G?”

It turns out that there’s a perfectly logical explanation. 

Several key mathematical ideas came from Arabic speaking mathematicians, including using a variable to represent an unknown. Spanish mathematicians adopted this idea. 

But the problem was, lots of Arabic words and sounds have no equivalent in Spanish. So the Spanish did their best and chose the closest sounding word to the Arabic word for some unknown, which was the “ch” sound in classical Greek. 

This is represented by the Greek “X.” 

Later, when it was translated into the common European language of the time, Latin, people simply changed the Greek X to the Latin X. 

And that’s why we use X to this day.

Now, a more interesting question might be, why didn’t we think to ask where X came from? 

What other questions should we be asking?

Thanks for being curious!

With excitement,

Anwell Tsai