Expressions

An expression is a combination of numbers, variables, and operations that represents a value. Unlike an equation, an expression has no equals sign — it's a phrase, not a sentence.

Examples:

• $3 + 5$ — a numeric expression (evaluates to $8$)
• $2x + 1$ — an algebraic expression (depends on $x$)
• $x^2 - 4$ — a polynomial expression

Terms are the parts separated by $+$ or $-$. In $2x + 1$, the terms are $2x$ and $1$.