Variables & Expressions
What are Variables?
A variable is a symbol (usually a letter) that represents an unknown value or a value that can change. In algebra, we often use letters like x, y, and z to represent variables.
Variables can represent different values in different situations.
For example, in the expression 2x + 3, the variable x can be any number.
Variables are essential in mathematics because they allow us to write general formulas and solve problems where some values are unknown.
Algebraic Expressions
An algebraic expression is a combination of variables, numbers, and operations. Expressions do not include equal signs.
Examples of Expressions
Parts of an Expression
Evaluating Expressions
To evaluate an expression means to find its value by substituting specific values for the variables.
Example 1: Evaluate 2x + 3 when x = 4
Example 2: Evaluate 3a - 5b when a = 2 and b = 3
Example 3: Evaluate x² + 2x - 1 when x = -3
Practice Variables
Test your knowledge with our interactive variable and expression practice exercises.
Start Practice