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Combining equations

  1. Sep 15, 2014 #1
    i have two equations:
    D=AF (A is a constant)
    D=BL^3 (B is a constant)
    I'm trying to combining them and use a third variable to get a relationship between D F and L
    I've tried AF=BL^3
    A/B=(l^3)/F
    but I'm stuck
     
  2. jcsd
  3. Sep 15, 2014 #2

    mfb

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    2016 Award

    Staff: Mentor

    You cannot solve those equations - you have three unknown variables and just two equations.

    You can get a single equation where all variables appear, but how would that help? As an example, start with 2D=2BL3 and replace 2D = D+D = D+AF to get D+AF=BL3
     
  4. Sep 16, 2014 #3
    If all you want is a relationship between the three variables, you can add the two equations together and get

    2D = AF + BL^3

    D = (AF + BL^3)/2

    You could probably graph this three-dimensionally, but you'll need a third equation to solve it definitively.
     
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