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Topic: find x (Read 340 times) |
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tony123
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| « Last Edit: Jan 16th, 2008, 12:05pm by tony123 » |
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towr
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Re: find x
« Reply #1 on: Jul 1st, 2007, 10:32am » |
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Seems like you could bring it back to a simple quadratic. Repeating the same bit thrice is just superfluous.
And why link to an image, and not just write it?
x =  (-3 + 4 (-3 + 4 (-3 + 4 x )))
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Sir Col
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Re: find x
« Reply #2 on: Jul 1st, 2007, 11:45am » |
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I suspect he used the image to ensure that the nested radicals were conveyed properly, and the repetition is to obfuscate the trick.
This is an interesting variation of an old puzzle. It is classically presented, as an interview question at the "better" universities in England, as, x = sqrt(2 + sqrt(2 + sqrt(2 + ..., and having the single clearly defined limit, x = 2. However, this one is a little different and has quite a string in the tail.
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towr
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Re: find x
« Reply #3 on: Jul 2nd, 2007, 1:37am » |
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on Jul 1st, 2007, 11:45am, Sir Col wrote:| However, this one is a little different and has quite a string in the tail. |
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Well x=1 and x=3 are clearly solutions. And drawing the graphs suggest they're the only two real ones.
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