Basic Concepts
In a nutshell: Variables and expressions help describe unknowns and solve real-world problems.
## What Are Expressions and Variables?
An **expression** is a math sentence with numbers, variables (like \(x\) or \(y\)), and operations. A **variable** stands in for a number you don't know yet.
## Why Use Variables?
Variables let us describe patterns, solve puzzles, and write rules. They're like mystery boxes!
## Writing Expressions
You can write an expression like \(2x + 5\) (which means "2 times a number plus 5").
## Real-Life Connections
Algebra helps you figure out things like "How many tickets can I buy with \$20 if each ticket costs \(x\) dollars?"
Examples
- If you have \(x\) apples and buy 3 more, you have \(x + 3\) apples.
- If each t-shirt costs $8, the cost for \(n\) shirts is \(8n\).