# What is a Variable?

Variables are a foundational concept in algebra. It is called a variable because its value can vary from one equation to another (perhaps even within a single equation). The most common variable you will come across is ‘*x*‘. It is commonly used to represent unknowns in equations. For example, 6*x*+1=15. The variable *x* can be solved by performing algebraic operations on both sides of the equation. Some equations have multiple variables.

## Variables

In this video, I want to talk a little bit about variables. Variables are a foundational concept in algebra, so it’s important to get a good grasp of what they are before moving forward.

A variable is called a variable because its value can vary from one equation to another, or in some cases even within a single equation its value can vary.

**The most common variable you’ll encounter is x.** X is commonly used to represent unknowns in an equation. Let’s say we had the equation 6x plus 1 equals 15.

This is an example of a simple sort of equation where you can solve for x by performing algebraic operations on both sides of the equation here.

This is this is a single variable equation, so x is the only variable here. You can solve for x. X has a single value. I might then move on to another equation that was 4x minus 3 equals 5.

X would have a different value in this equation from the equation above. There are also equations that have multiple variables.

If you have that, say for instance you have y equals 3x minus 1. X is not just a single variable in this equation. X is a whole set of variables that correspond to individual y variables.

I don’t want to go into a whole lot of detail about this right now, but x represents multiple values in this set. It’s varying even within this equation.

**Variables are used for representing numbers that either we don’t know or that have multiple values that we can’t represent with actual constants.**

We’re going to be encountering them a lot as we move forward here in algebra, so it’s important to just have a good foundation as to what they are and what they can be used for.