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Homework Help: Inverse Variation

  1. Aug 17, 2010 #1
    1. The problem statement, all variables and given/known data

    If y varies inversely as the square of x, and y = 1/8 when x = 1, find y when x = 5.

    y = 8/25
    y = 1/200


    3. The attempt at a solution
    The equation to find this is y=k/x, I know that. I've tried to plug in both given answers to see which ones matched but neither of them did. I'm not sure what to plug in for k or x. I just need someone to correctly set this up for me and I'll be able to solve it.
     
  2. jcsd
  3. Aug 17, 2010 #2

    Mark44

    Staff: Mentor

    No, it says that y varies inversely as the square of x.
     
  4. Aug 17, 2010 #3

    rock.freak667

    User Avatar
    Homework Helper


    3. The attempt at a solution
    The equation to find this is y=k/x[/QUOTE]

    You'll need to try again, if the cube of x is x3, the square of x is?
     
  5. Aug 17, 2010 #4
    x2

    So if I square 5 and cross multiply it's 8/25. Is that right?
     
    Last edited: Aug 17, 2010
  6. Aug 17, 2010 #5

    Mark44

    Staff: Mentor

    No, it's not. You skipped some steps. First, what is the equation? And you know that when x = 1, y = 1/8.
     
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