Why is x so important

The origin of X

But, how was it created? X is derived from the Phoenician letter samekh, meaning "fish." Originally used by the Phoenicians to represent the / s / consonant (denoting a hard S sound), the Greeks borrowed the samekh around 900 BC and named it Chi.

X is a variable and fills in for a missing number. X is just the most common variable you see in math