Math glossary
Every term in plain English, with the notation, an example, and the confusion it usually causes. If a word stopped you mid-lesson, it is here.
16 terms
A
- Absolute value
- The absolute value of a number is its distance from zero on the number line. Distance ignores direction, so it is never negative: both 5 and -5 have absolute value 5.
C
- Coefficient
- A coefficient is the number multiplying a variable in a term. In 3x the coefficient is 3, and in -5y it is -5, because the sign belongs to the number.
- Constant
- A constant is a term with a fixed value and no variable attached. In 3x + 7, the constant is 7, because it stays the same whatever x turns out to be.
D
- Discriminant
- The discriminant is the expression b squared minus 4ac inside the quadratic formula. Its sign tells you how many real solutions a quadratic has before you finish solving.
- Distributive property
- The distributive property says a(b + c) = ab + ac. The multiplier outside the parentheses multiplies every term inside, not only the first one.
E
- Equation
- An equation is a statement that two expressions are equal, joined by an equals sign. Solving one means finding every value of the variable that makes the statement true.
I
- Inverse operations
- Inverse operations undo each other. Addition and subtraction are inverses, and so are multiplication and division. Solving an equation means applying the inverse of whatever was done to the variable.
L
- Like terms
- Like terms have exactly the same variables raised to exactly the same powers. 3x and 5x are like terms, but 3x and 3x squared are not, and neither are 3x and 7.
- Linear equation
- A linear equation is one whose graph is a straight line. Every variable appears to the first power only, so there are no squares, roots, or variables in a denominator.
Q
- Quadratic equation
- A quadratic equation is one that can be written as ax squared plus bx plus c = 0, with a not equal to zero. The squared term is what makes it quadratic rather than linear.
S
- Slope
- Slope measures how steep a line is: the change in y divided by the change in x. A slope of 2 means the line climbs 2 units for every 1 unit across.
- Solution set
- The solution set is every value that makes an equation or inequality true. An equation often has one solution, an inequality usually has infinitely many, and some have none at all.
T
- Term
- A term is one piece of an expression, separated from the others by plus or minus signs. The expression 4x + 12 - 2x has three terms: 4x, 12 and -2x.
V
- Variable
- A variable is a letter standing in for a number you do not know yet, or one that can change. In x + 3 = 10, the variable x represents the single number that makes the sentence true.
Y
- y-intercept
- The y-intercept is where a graph crosses the vertical axis — the value of y when x is 0. In y = 2x + 3 the y-intercept is 3, so the line passes through (0, 3).
Z
- Zero product property
- The zero product property says that if a product equals zero, at least one of its factors must be zero. It is the reason factoring solves quadratic equations.