### Arithmetic Sequence

A sequence of numbers in which the difference between any two consecutive terms is the same.

### Average Rate of Change

The change in the value of a quantity by the elapsed time. For a function, this is the change in the y-value divided by the change in the x-value for two distinct points on the graph.

### Constant Rate of Change

With respect to the variable x of a linear function y = f(x), the constant rate of change is the slope of its graph.

### Domain

The set of x-coordinates of the set of points on a graph; the set of x-coordinates of a given set of ordered pairs. The value that is the input in a function or relation.

### Explicit Expression

A formula that allows direct computation of any term for a sequence a1, a2, a3, . . . , an, . . . .

### Exponential Function

A nonlinear function in which the independent value is an exponent in the function, as in y = abx.

### Exponential Model

An exponential function representing real-world phenomena. The model also represents patterns found in graphs and/or data.

### Expression

Any mathematical calculation or formula combining numbers and/or variables using sums, differences, products, quotients including fractions, exponents, roots, logarithms, functions, or other mathematical operations.

### Even Function

A function with a graph that is symmetric with respect to the y-axis. A function is only even if and only if f(-x) = f(x).

### Factor

For any number x, the numbers that can be evenly divided into x are called factors of x. For example, the number 20 has the factors 1, 2, 4, 5, 10, and 20.

### Geometric Sequences

A sequence of numbers in which the ratio between any two consecutive terms is the same. In other words, you multiply by the same number each time to get the next term in the sequence. This fixed number is called the common ratio for the sequence.

### Interval Notation

A notation representing an interval as a pair of numbers. The numbers are the endpoints of the interval. Parentheses and/or brackets are used to show whether the endpoints are excluded or included.

### Linear Model

A linear function representing real-world phenomena. The model also represents patterns found in graphs and/or data.

### Odd Function

A function with a graph that is symmetric with respect to the origin. A function is odd if and only if f(-x) = -f(x).

### Parameter

The independent variable or variables in a system of equations with more than one dependent variable.

### Recursive Formula

A formula that requires the computation of all previous terms to find the value of an.

### Term

A value in a sequence--the first value in a sequence is the 1st term, the second value is the 2nd term, and so on; a term is also any of the monomials that make up a polynomial.