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Topic: equation of doom (Read 1073 times) |
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srn437
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equation of doom
« on: Sep 11th, 2007, 5:13pm » |
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x^y -y=x^5 -y^4 -y^3=20 x>0 y>0
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| « Last Edit: Sep 11th, 2007, 8:20pm by srn437 » |
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ThudnBlunder
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Re: <insert subject here>
« Reply #1 on: Sep 11th, 2007, 5:45pm » |
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You haven't written a subject title and you haven't written a question.
No question, no answer, dig? Subject titles are necessary so that one can easily find puzzles again. For instance, sometimes members might want to cite examples of puzzles posted by people who haven't a clue, and if you give your threads titles they can easily remember yours.
In fact, all you have done is steal Jock's sig and started an untitled lthread with it!
Please stop polluting this forum with your cretinous behaviour.
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| « Last Edit: Sep 12th, 2007, 7:40am by ThudnBlunder » |
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THE MEEK SHALL INHERIT THE EARTH.....................................................................er, if that's all right with the rest of you.
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srn437
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the dark lord rises again....
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Re: <insert subject here>
« Reply #2 on: Sep 11th, 2007, 7:14pm » |
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First of all, it is a question. I didn't steal the sig, I used it as a springboard(I stole the springboard). And this forum isn't polluted. Why is your ambition to destroy my mind(not that it's working)?!
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Grimbal
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Re: equation of doom
« Reply #3 on: Sep 12th, 2007, 2:54am » |
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Pieces of pie. 
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ThudnBlunder
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Re: <insert subject here>
« Reply #4 on: Sep 12th, 2007, 3:11am » |
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on Sep 11th, 2007, 7:14pm, srn347 wrote:| First of all, it is a question. |
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An equation is not a question. It is a statement.
If you use somebody's else's sig you ought to attribute it to them, not disingenuously post it as a question without a question mark.
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| « Last Edit: Sep 12th, 2007, 7:45am by ThudnBlunder » |
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THE MEEK SHALL INHERIT THE EARTH.....................................................................er, if that's all right with the rest of you.
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srn437
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Re: equation of doom
« Reply #5 on: Sep 12th, 2007, 8:16pm » |
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An equation is a question, asking what x and y are. And since you mentioned whos sig it is, I guess attribution is out of the question until next time.
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mikedagr8
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Re: equation of doom
« Reply #6 on: Sep 12th, 2007, 8:18pm » |
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on Sep 12th, 2007, 8:16pm, srn347 wrote:| An equation is a question, asking what x and y are. And since you mentioned whos sig it is, I guess attribution is out of the question until next time. |
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So in this equation "5*4=20" where are the x and y?
What you are after is instead of this
Quote:| x^y -y=x^5 -y^4 -y^3=20 x>0 y>0 |
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is this "x^y -y=x^5 -y^4 -y^3=20 ; x>0 y>0 "
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| « Last Edit: Sep 12th, 2007, 8:19pm by mikedagr8 » |
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"It's not that I'm correct, it's that you're just not correct, and so; I am right." - M.P.E.
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srn437
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the dark lord rises again....
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Re: equation of doom
« Reply #7 on: Sep 12th, 2007, 8:39pm » |
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5*4=20 is an identity, since x and/or y dropped out of the equation. They can be anything. Regardless, can any of you try the equation instead of obsessing over the fact that it is someones sig?
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Grimbal
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Re: equation of doom
« Reply #8 on: Sep 13th, 2007, 1:19am » |
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Well, I gave up calculating an exact answer. The xy part makes it probably impossible.
But numerically, I find an amusing result which I hinted at.
x and y are close to pi and e .
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srn437
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Re: equation of doom
« Reply #9 on: Sep 13th, 2007, 4:44pm » |
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Possibly. x^y isn't what makes it nearly impossible, x^5-y^4-y^3 is.
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Obob
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Re: equation of doom
« Reply #10 on: Sep 13th, 2007, 6:32pm » |
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No, the x^y is much more difficult to deal with. In fact, x^5-y^4-y^3=20 allows you to eliminate one of the variables.
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ThudnBlunder
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Re: equation of doom
« Reply #11 on: Sep 13th, 2007, 6:48pm » |
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on Sep 12th, 2007, 8:16pm, srn347 wrote:| An equation is a question, asking what x and y are. |
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It is a question only in that we must try to figure out what x and y are allowed to be, eg. integers, reals, etc.
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THE MEEK SHALL INHERIT THE EARTH.....................................................................er, if that's all right with the rest of you.
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srn437
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Re: equation of doom
« Reply #12 on: Sep 13th, 2007, 9:22pm » |
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They have to be more than zero(clearly). Other than that, try to keep it real(especially an integer), but if you find any other solution, try it anyway.
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towr
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Re: equation of doom
« Reply #13 on: Sep 14th, 2007, 5:47am » |
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You can rework the equations to
x = (y^4 +y^3 +20)^(1/5)
y = log(y +20)/log(x)
and use these to iteratively approximate x and y
giving (in my case, using javascript and 100 iterations)
2.718300263323929 and 3.1416110348231654
As Grimbal said, pretty much e and pi respectively.
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| « Last Edit: Sep 14th, 2007, 5:48am by towr » |
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srn437
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the dark lord rises again....
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Re: equation of doom
« Reply #14 on: Sep 15th, 2007, 3:51pm » |
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I've tried it. It is about equal to 20 in that case, but not exactly.
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towr
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Re: equation of doom
« Reply #15 on: Sep 16th, 2007, 12:26pm » |
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Well, that's why it's called an approximation.
I doubt there is a (simple) exact answer. (You could give an exact answer using e.g. limits, but that wouldn't be very informative)
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Sameer
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Re: equation of doom
« Reply #16 on: Sep 16th, 2007, 12:47pm » |
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on Sep 13th, 2007, 9:22pm, srn347 wrote:| They have to be more than zero(clearly). Other than that, try to keep it real(especially an integer), but if you find any other solution, try it anyway. |
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You got an integer solution? I would like to see that!!! And no one liners: proper method and explanation!!
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ThudnBlunder
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Re: equation of doom
« Reply #17 on: Sep 16th, 2007, 1:55pm » |
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on Sep 16th, 2007, 12:47pm, Sameer wrote:
You got an integer solution? I |
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He ain't got zip! He just likes asking questions he doesn't understand.
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THE MEEK SHALL INHERIT THE EARTH.....................................................................er, if that's all right with the rest of you.
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srn437
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the dark lord rises again....
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Re: equation of doom
« Reply #18 on: Sep 16th, 2007, 4:11pm » |
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I have more than zip! Though the part about me not knowing the answer is correct. The next question I ask will have an answer I know of, if it has an answer...
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