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Math Help - Quick Graphing Question

  1. #1
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    Quick Graphing Question

    Thanks in advance to anyone who let's me know if I'm right or where I went wrong!

    Basically I have a system of equations with two equations:

    x + y = 2

    2y = -5x + 10

    I have to graph both of these equations. For some reason the first equation (equations that just have plain letters without numbers lol) always throws me off, and I just want to make sure I'm doing things right.

    I have attached a picture with how I did the graph (just assume each square is a measurement of 1).

    So if I'm right, the point of intersection would be (2,0).

    PICTURE: Lines_zpsf77df808.png Photo by Azuraiiii | Photobucket
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  2. #2
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    Re: Quick Graphing Question

    Your graph is wrong, the two lines you have are y = -x + 2 and y = -10x + 5. You graphed y = -x + 2 correctly but not the other line. You would be correct if it was y=-5x + 10 rather than 2y = -5x+ 10. Your intersection is also wrong as well. -x + 2 = -10x + 5, so x = 1/3, making y = 5/3. The intersection is (1/3, 5/3).
    Thanks from Asthuran00
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  3. #3
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    Re: Quick Graphing Question

    Thanks bud, appreciated!


    But there's still one thing I don't get. You said the second line I have is "y = -10x + 5". Now if I'm starting with "2y = -5x + 10" wouldn't i divide both sides by 2 to isolate y which would give me "y = -5/2x + 5" ?

    I'm not sure where you're getting the "y = -10x + 5" from if the original equation is 2y = -5x + 10. Maybe I'm just having a moment, who knows, but if you could clarify that it'd really help me out!

    PS: in my graph drawing I got the lines backwards, I put the wrong labelling haha sorry, so assume I put the labels on the opposite lines.
    Last edited by Asthuran00; June 28th 2013 at 06:59 PM.
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  4. #4
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    Re: Quick Graphing Question

    So there's no confusion, I updated the picture so that it has my new graph that I drew. If that one is still wrong please let me know haha.

    Lines_zps57276cc4.png Photo by Azuraiiii | Photobucket
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  5. #5
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    Re: Quick Graphing Question

    Sorry about that, I multiplied by 2 rather than divided by 2. You are right that the line will be y = -5/2 x + 5. Setting the equations equal, x = 2, y = 0. (2,0) is the intersection. You were correct. Your new graph is correct.
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  6. #6
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    Re: Quick Graphing Question

    Thanks bud, very much appreciated!
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