Domain: the domain or set of departure of a function is the set into which all of the input of the function is constrained to fall. It is the set X in the notation f: X → Y, and is alternatively denoted as . Since a (total) function is defined on its entire domain, its domain coincides with its domain of definition.
Vertical Line test: the vertical line test is a visual way to determine if a curve is a graph of a function or not. A function can only have one output, y, for each unique input, x. If a vertical line intersects a curve on an xy-plane more than once then for one value of x the curve has more than one value of y, and so, the curve does not represent a function. If all vertical lines intersect a curve at most once, then the curve represents a function.
Relation: Relations are used to describe a connection between the elements of two sets. They help to map the elements of one set (known as the domain) to elements of another set (called the range) such that the resulting ordered pairs are of the form (input, output).
Practical Range: range is a statistical measurement of dispersion, or how much a given data set is stretched out from smallest to largest. In a set of data, the range is the difference between the greatest and smallest value.
Function: Function is an expression, rule, or law that defines a relationship between one variable (the independent variable) and another variable (the dependent variable).
Practical Domain: The domain is the set of all possible x-values which will make the function "work" and will output real y-values.
function Notation: Function notation is a way of expressing a relationship between two variables. A function is most often denoted by letters such as f, g, and h, and the value of a function f at an element x of its domain is denoted by f(x). In function notation, f(x) represents the output of the function f for a given input x. The letter 'f' is commonly used to represent a function, but other lower case letters such as 'g' or 'h' can also be used. The function notation formula is f(x) = y, where y is the output of the function for a given input x. The set of all pairs (x, f(x)) is called the graph of the function.