face
One of the plane surfaces of a polyhedron.

factor
n. A factor of a number n is a number (usually taken to be positive) that divides n exactly. For example, the factors of 18 are 1, 2, 3, 6, 9, and 18. Similarly, a factor of a polynomial P(x) is a polynomial that divides P(x) exactly. Thus x and x - 1 are two of the factors of .
v. To factor a number or polynomial is to express it as a product of basic terms. For example, factors as x(x - 1)(x + 1).

Factor Theorem
If P(x) is a polynomial, and a is a root of the equation P(x) = 0, then
x - a is a factor of P(x).

factor(s)
Numbers multiplied to produce a specific product. For example:

2 X 3 X 3 = 18: factors are 2 and 3; (x - 2) and (x + 1) are factors of

first-hand data
Data collected by an individual directly from observations or measurements.

flip
Another word for reflection.

fractal
Very roughly, a set of such a jagged and fractured appearance that small parts of it, however magnified, have the same complexity as the whole.

frequency diagram
A diagram used to record the number of times various events occurred.

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function
A rule that produces, for any element x of a certain set A, an object f(x). The set A is the domain of the function; the set of values taken on by f(x) is the range of the function.

More formally, a function is a collection of ordered pairs (x, y) such that the second entry y is completely determined by the first entry x.

function notation
If a quantity y is completely determined by a quantity x, then y is called a function of x. For example, the area of a circle of general radius x might be denoted by A(x) ( pronounced "A of x.) In this case, .

fundamental counting principle
If an event can happen in x different ways, and for each of these ways a second event can happen in y different ways, then the two events can happen in x X y different ways.