Drexel dragonThe Math ForumDonate to the Math Forum

Ask Dr. Math - Questions and Answers from our Archives
_____________________________________________
Associated Topics || Dr. Math Home || Search Dr. Math
_____________________________________________

Recognizing a Function From a Graph

Date: 09/03/2003 at 02:23:55
From: flora
Subject: Explain how to tell if a graph represents a function

I think I'm a bit confused about what a function is. How is it 
different from an equation?


Date: 09/03/2003 at 06:13:13
From: Doctor Anthony
Subject: Re: Explain how to tell if a graph represents a function

A function requires that you get a single unique value of y for a 
given value of x.  So if you draw a line, x=k (that is, a line 
parallel to the y axis), and it cuts the graph in one point only for 
all k, then you have a function.  If the line cuts the graph in more 
than point for some values of k then we have a RELATION and not a 
function.

Example of a function:   y = 3x^2 + 2x - 1

Example of a relation:   x^2 + y^2 = 4

- Doctor Anthony, The Math Forum
  http://mathforum.org/dr.math/ 


Date: 09/04/2003 at 00:54:54
From: flora
Subject: Thank you 

Thanks!  That was very clear!
Associated Topics:
High School Definitions
High School Functions

Search the Dr. Math Library:


Find items containing (put spaces between keywords):
 
Click only once for faster results:

[ Choose "whole words" when searching for a word like age.]

all keywords, in any order at least one, that exact phrase
parts of words whole words

Submit your own question to Dr. Math

[Privacy Policy] [Terms of Use]

_____________________________________
Math Forum Home || Math Library || Quick Reference || Math Forum Search
_____________________________________

Ask Dr. MathTM
© 1994-2013 The Math Forum
http://mathforum.org/dr.math/