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Thread: Can you find a pattern in this?

  1. #1

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    Frenzied Member System_Error's Avatar
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    Can you find a pattern in this?

    With this equation, is there some sort of pattern that leads to the points that work?

    x^y=y^x

    I mean, I know that if x and y are the same, that the answer will be the same, but there are some others that work(2,4)...So is there some kind of pattern to this?

  2. #2
    Super Moderator manavo11's Avatar
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    Re: Can you find a pattern in this?

    Only thing I can think of is to use a logarithm...

    Ln(x^y)=Ln(y^x)
    y*Ln(x)=x*Ln(y)
    y/x = Ln(y)/Ln(x)

    If that helps to get any more results... It's the only way I can think of to simplify/change it...


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  3. #3

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    Frenzied Member System_Error's Avatar
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    Re: Can you find a pattern in this?

    Quote Originally Posted by manavo11
    Only thing I can think of is to use a logarithm...

    Ln(x^y)=Ln(y^x)
    y*Ln(x)=x*Ln(y)
    y/x = Ln(y)/Ln(x)

    If that helps to get any more results... It's the only way I can think of to simplify/change it...

    Thank you, I'm thinking that their is no pattern, and their probably isn't. I made a program that gave me all the coordinates that worked up to a certain point, and they all looked completely random. I just saw this problem on another website, and wondered if their was some kind of pattern, but I guess their's not.

  4. #4
    pathfinder NotLKH's Avatar
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    Re: Can you find a pattern in this?

    Looks to me that,
    for a specific M, there exists an A;
    A = M(1/(M-1))

    And from this you can get a B:
    B = AM

    which A and B then satisfies:

    AB= BA



    *************************************
    So for example, if we want to find A, Given M = 2:

    A = 2^(1/(2-1)); or A = 2.

    Thus, B = A*M, or 4,
    and we see that
    A^B = B^A is valid, or 2^4 = 4^2

    ***********Or, Another Example:******************
    Lets say M = 7, that makes:
    A = 1.3830875542684884926406585135348

    And then:
    B = 9.6816128798794194484846095947438

    So, does A^B = B^A?

    A^B = 23.102129367646701645408458653
    B^A = 23.102129367646701645408458653

    Yep!


  5. #5

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    Re: Can you find a pattern in this?

    Quote Originally Posted by NotLKH
    Looks to me that,
    for a specific M, there exists an A;
    A = M(1/(M-1))

    And from this you can get a B:
    B = AM

    which A and B then satisfies:

    AB= BA



    *************************************
    So for example, if we want to find A, Given M = 2:

    A = 2^(1/(2-1)); or A = 2.

    Thus, B = A*M, or 4,
    and we see that
    A^B = B^A is valid, or 2^4 = 4^2

    ***********Or, Another Example:******************
    Lets say M = 7, that makes:
    A = 1.3830875542684884926406585135348

    And then:
    B = 9.6816128798794194484846095947438

    So, does A^B = B^A?

    A^B = 23.102129367646701645408458653
    B^A = 23.102129367646701645408458653

    Yep!


    Wow! You are extremely smart, I know I couldn't do that. Thank you very much!

  6. #6
    pathfinder NotLKH's Avatar
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    Re: Can you find a pattern in this?

    OOPS!
    Sorry, I realized that I didn't show how I got the A M Relationship.

    Lets say, for some A,B, that:
    AB = BA

    Certainly, then, for some M,
    AM= B

    And for some R:
    (AM)R = BR

    Or:
    ARM=BR

    So, if the two equations are identical, or:
    ARM = BR <==> AB = BA

    Then, equivalently:
    RM = B and A = R.
    Or...
    AM = B

    Now, Going back to the equation AM= B, we see that
    AM= AM

    Divide both sides by A, or actually multply both sides by A-1:
    AM-1=M

    Now, take the M-1 root of both sides:

    (AM-1)(1/(M-1)) = M(1/(M-1))

    Which then gives us, for some M:
    A = M(1/(M-1))

    Thus, for some M, we have an A, B such that AB=BA when:

    A = M(1/(M-1))
    B = AM = M*[M(1/(M-1))] = M(M/(M-1))


  7. #7

  8. #8
    pathfinder NotLKH's Avatar
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    Re: Can you find a pattern in this?

    Hmmm,
    Here's a neet way to say the same thing:

    If we say A = (1/a)
    And B = (M/a)

    it can be worked out that M*(aM-1) = 1.

    So, if M = 2, 3, 4, ...
    Then a = (1/2), sqrt(1/3), cuberoot(1/4), ...


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