# Obtain information from or about the graph of a functional relationship

A "relation" is just a relationship between sets of information. point, we know exactly where to go; given an x, we get only and exactly one y. This graph shows a function, because there is no vertical line that will cross this graph twice. oval. Here two relations consisting of seven ordered pair solutions are obtained: .. state the domain and range and determine whether or not it represents a function . In mathematics, the graph of a function f is, formally, the set of all ordered pairs (x, f(x)), such To test whether a graph of a relation represents a function of the first variable x, one uses the vertical line test. To test The graph of a function on its own doesn't determine the co-domain. .. Visualization of technical information.

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## Graph of a function

In mathematics, the graph of a function f is, formally, the set of all ordered pairs x, f xsuch that x is in the domain of the function f, and, in practice, the graphical representation of this set. If the function input x, and the values f xare real numbersthe graph is a two-dimensional graphand, for a continuous functionis a curve.

If the function input x is an ordered pair x1, x2 of real numbers, the graph is the collection of all pairs x1, x2f x1, x2. These pairs can be identified with the ordered triples x1, x2, f x1, x2. For a continuous function the graph of such a function is a surface.

The concept of the graph of a function is generalized to the graph of a relation. It is usually symbolized as in which x is called argument input of the function f and y is the image output of x under f. Functions and their graphs A single output is associated to each input, as different input can generate the same output.

The set X is called domain of the function f dom fwhile Y is called codomain cod f. A glance at the graphical representation of a function allows us to visualize the behaviour and characteristics of a function.

### Recognizing functions from graph (video) | Khan Academy

Functions and their graphs: Essentially, the test amounts to answering this question: If so, then the curve is not the graph of a function. If it is not possible, then the curve is the graph of a function.

Why does this test work? A curve would fail to be the the graph of a function if for any input x, there existed more than one y-value corresponding to it.

### Functions and Graphs

Vertical line test Take, for example, the equation Note that the points 0, 2 and 0, -2 both satisfy the equation. So if a vertical line hits a curve in more than one place, it is the same as having the same x-value paired up with two different y-values, and the graph is not that of a function.

Thus, a circle is not the graph of a function. Vertical line test We see that we can draw a vertical line, for example the dotted line in the drawing, which cuts the circle more than once.