Six Important Algebra Terms You Must Know for the ACT
Algebra is chockfull of words that are useful but often misunderstood. To do well on the ACT Math test, you should be able to define these important terms: variable, constant, equation, expression, term, and coefficient.

Variable. A variable is any letter that stands for a number. The most commonly used letters are x and y, but you can use any letter.

Constant. A constant is a number without a variable. For example: The equation 6m + 7 = –m has one constant, the number 7.

Equation. An equation is any string of numbers and symbols that makes sense and includes an equal sign. For example, here are three equations:

Expression. An expression is any string of numbers and symbols that makes sense when placed on one side of an equation. For example, here are four expressions:

Term. A term is any part of an expression that’s separated from the other parts by either a plus sign (+) or a minus sign (–). Important: A term always includes the sign that immediately precedes it. For example,

The expression 3x – 7 has two terms: 3x and –7.

The expression –x^{2} – 9x + 11 has three terms: –x^{2}, –9x, and 11.

The expression
has one term:


Coefficient. A coefficient is the numerical part of a term, including the sign that precedes it (+ or –). Important: Every term has a coefficient. When a term appears to have no coefficient, its coefficient is either 1 or –1, depending on the sign. For example,

The term 3x has a coefficient of 3.

The term –9x has a coefficient of –9.

The term –x^{2} has a coefficient of –1.

Being clear about the meanings of these six words can help you with any other math you study.