# What is a Variable? | Best Algebra Review

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.

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Last updated: 11/30/2018