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Direct Variation

  1. Jun 18, 2005 #1
    I am having alot of difficulty with this problem . I don't have the slightest idea on how to do this problem and my textbook does not explain it. Please help me:


    Determine whether 1 - y = 2x is a direct variation. If so explain.


    This problem has me stumpted and very frustrated. :confused:
     
  2. jcsd
  3. Jun 18, 2005 #2
    A relationship between two variables such that the data increase or decrease together at a constant rate is called direct variation.

    When x increases or decreases, what happens to y?
    Is there a constant relationship between x and y?
     
  4. Jun 18, 2005 #3

    HallsofIvy

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    It never ceases to amaze me that people think they should be able to do a problem in which they don't know what the key words mean.

    The whole point of this question is the definition "direct variation". As whozum said "A relationship between two variables such that the data increase or decrease together at a constant rate is called direct variation.
    (I emphasized the crucial part.)

    Whozum then asks "When x increases or decreases, what happens to y?
    Is there a constant relationship between x and y?". I'll be more specific: when x= 1 what is y? When x doubles to 2, what is y? Did y also double? Is this "direct variation"?
     
  5. Jun 18, 2005 #4
    I don't mean to be a pest, but I still do not comprehend how to do this problem. Can I get a little more help. :redface:
     
  6. Jun 18, 2005 #5

    HallsofIvy

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    Start by answering as many of the questions I asked as you can!
     
  7. Jun 18, 2005 #6
    I know what the words mean, I just don't know how to solve the problem. I read the same definitions in the chapter. But the book doesn't show me how to solve the problem. If you can be so kind and help me start the problem I'd appreciate it.
     
  8. Jun 18, 2005 #7

    HallsofIvy

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    Alright, I'll give you one more chance!
    Answer these questions:
    What is f(1)?

    What is f(2)?

    2 is exactly twice 1. Is f(2) exactly twice f(1)?
     
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