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Thread: Domain and Range using Interval Notation

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    Domain and Range using Interval Notation

    I need help finding the domain and range of a graph using interval notation.

    I have the points (-2,0), (1,4), (2,1), and (4,-1) and there are no arrows on the lines. How do I find the domain and range of these points using interval notation?

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    Quote Originally Posted by Kat13V View Post
    I need help finding the domain and range of a graph using interval notation.

    I have the points (-2,0), (1,4), (2,1), and (4,-1) and there are no arrows on the lines. How do I find the domain and range of these points using interval notation?
    If your relation consists of only these four discrete points, there are no "intervals." Your domain is the x values and range is the y values.

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    Quote Originally Posted by wjm11 View Post
    If your relation consists of only these four discrete points, there are no "intervals." Your domain is the x values and range is the y values.
    I'm not looking for the intervals though. I'm looking for the domain and range of the line the points are on. But my teacher wants them to be found using interval notation. I've found lots of examples for finding the domain and range of a graph using interval notation, but all the graphs are of parabolas. My graph isn't of a parabola.

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    Quote Originally Posted by Kat13V View Post
    I'm not looking for the intervals though. I'm looking for the domain and range of the line the points are on. But my teacher wants them to be found using interval notation. I've found lots of examples for finding the domain and range of a graph using interval notation, but all the graphs are of parabolas. My graph isn't of a parabola.
    Check out the figure at the top of this page: http://www.mathsisfun.com/sets/domai...-codomain.html

    If that is the situation you are trying to describe, then the figure shows you the domain and range.

    You can also find many examples of domain and range and interval notation here: http://cnx.org/content/m13596/latest/

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    Quote Originally Posted by Kat13V View Post
    I need help finding the domain and range of a graph using interval notation.

    I have the points (-2,0), (1,4), (2,1), and (4,-1) and there are no arrows on the lines. How do I find the domain and range of these points using interval notation?
    Do you mean that (-2, 0), (1, 4), (2, 1) and (4, -1) are points on a graph with lines connecting them? It makes no sense to talk about "domain and range of these points". Relations and functions have "domain" and "range", not points. If that is what you mean, then domain is the interval from the smallest of the "x" values (-2, 1, 2, 4) to the largest and the rangle is the interval from the smallest of the "y" values (-2, 1, 2, -1) to the largest.

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