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I can't understand this linear equation at all

  1. Feb 4, 2013 #1
    1. The problem statement, all variables and given/known data
    Alright...

    3x - 6y = 0, Graph the linear equation, finding it's intercepts.




    2. Relevant equations
    I've tried solving it by putting 0 in for x / y, and I've also tried putting -2 in for x / y, so that y = 2 when I move it over, and the system for my college homework tells me it's wrong either way. I simply don't get it.


    3. The attempt at a solution
    Quite obviously, if I try to solve it, I get 0,0. However, I have no idea how to get any other problem solution at all... If I put 0 in for x or y to simply get one variable, it ends up being y = 0, or x = 0... But it's telling me I have to graph multiple points. How would I do this?
     
  2. jcsd
  3. Feb 4, 2013 #2

    jedishrfu

    Staff: Mentor

    you have the equation of a line going thru the origin 0,0 so now can you see what the slope of the line is?

    Also can you see other points that might be on the line say pick x=2 then what is y?...
     
  4. Feb 4, 2013 #3

    SteamKing

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    Staff Emeritus
    Science Advisor
    Homework Helper

    It might help to put the original equation for the line into standard form,

    y = ax + b

    From this, you are able to determine the slope, a,and the y-intercept, b

    You can also generate points and plot the line.
     
  5. Feb 5, 2013 #4
    It's already in standard form, what are you talking about?

    y = mx + b is slope intercept......

    Ax + By = C is standard form, and it's in standard form already....
     
  6. Feb 5, 2013 #5
    Just convert your equation to intercept form. Using that you can graph by just knowing two points. Intercept form is x/a + y/b=1
     
  7. Feb 5, 2013 #6

    HallsofIvy

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    Staff Emeritus
    Science Advisor

    So the line goes through the point (0, 0) (and give both x and y intercepts)

    When you put -2 for x, you get -6- 6y= 0

    You get 6y= -6. That does NOT give y= 2. Try again.

    Well, yes, a line is determined by two points. One of those points is (0, 0). To get another point put in any value of x you like. x= -2 works fine but you have to solve the equation for y correctly!
     
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