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Math Help - Drawing a graph

  1. #1
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    Drawing a graph

    How can I draw the graph of |xy| <=0
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  2. #2
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    Re: Drawing a graph

    Quote Originally Posted by kastamonu View Post
    How can I draw the graph of |xy| <=0
    In order for |xy|\le 0 it is necessary for xy=0.

    Therefore, x=0\text{ or }y=0.
    Thanks from HallsofIvy
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    Re: Drawing a graph

    So the graph is two intersecting straight lines.
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    Re: Drawing a graph

    There is no way to graph this. It is wrong. The | xy| is > =0 for every x,y and not <0
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    Re: Drawing a graph

    Quote Originally Posted by MINOANMAN View Post
    There is no way to graph this. It is wrong.
    Why in the world would you post that?

    \{(x,y) : x = 0 \vee y = 0\} is the graph in \mathbb{R}^2
    This is the union of the x\text{-axis}~\&~y\text{-axis}~.

    \{(x,y,z) : x = 0 \vee y = 0\} is the graph in \mathbb{R}^3
    This is the union of the xz\text{-plane}~\&~yz\text{-plane}~.

    There were two correct replies posted. Are you saying that both Prof Halls and I are mistaken?
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    Re: Drawing a graph

    the |x| is never negative as simple as such..........the rest is blabla
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    Re: Drawing a graph

    Quote Originally Posted by MINOANMAN View Post
    the |x| is never negative as simple as such..........the rest is blabla
    Do you even the definition of a graph?
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    Re: Drawing a graph

    Quote Originally Posted by MINOANMAN View Post
    the |x| is never negative as simple as such..........the rest is blabla
    You are the one who is "blabla"ing. You seem to have misread the question. The original question was about graphing |xy|\le 0, the set of points (x, y) such that xy is either negative or zero. Yes, |xy| is never negative but it is 0. The graph is the two axes- the x- axis on which y= 0 so |xy|= |x(0)|= 0 and the y-axis on which x= 0 so |xy|= |(0)y|= 0.
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    Re: Drawing a graph

    Yes, |xy| is never negative but it is 0.......which implies x=0 and y=0..................I agree.....
    do not use the < 0 it is wrong............................................. ......
    and be more polite......after all we just exchange here views and ideas....and if we disagree in some issues this is just another expression of the plurality of Mathematics...
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    Re: Drawing a graph

    Quote Originally Posted by MINOANMAN View Post
    do not use the < 0 it is wrong...
    Again, why would any mathematically literate person write that?
    Now that is being as polite as this situation calls for.

    Did you miss read the OP?
    The OP was |xy|\le 0 not |xy|<0.
    If it had been the latter, then we all would agree that no nonempty graph exists.
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    Re: Drawing a graph

    Quote Originally Posted by HallsofIvy View Post
    So the graph is two intersecting straight lines.
    Many Thanks. At first I thought it was the graph of a hyperbolia. But I wasn't sure because of the absolute value sign.
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