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Posers and Puzzles

Posers and Puzzles

  1. 03 Jan '07 03:43 / 2 edits
    1.Differentiate sin inverse (x+1/x) with respect to x.
    2.what is the answer of the series
    (a-x)(b-x)(c-x)..............(z-x).
    3.integral of e to the power of x square dx.
    solve them and post the solution.
  2. 03 Jan '07 06:04
    I gave that up seven years ago, sorry.
  3. Standard member XanthosNZ
    Cancerous Bus Crash
    03 Jan '07 08:17
    1. (1-1/x^2)/(1-(x+1/x)^2)^(1/2)

    2. 0

    3. Doesn't exist
  4. 03 Jan '07 09:06
    Originally posted by XanthosNZ
    1. (1-1/x^2)/(1-(x+1/x)^2)^(1/2)

    2. 0

    3. Doesn't exist
    second and third are right but not the first.keep trying.
  5. Standard member XanthosNZ
    Cancerous Bus Crash
    03 Jan '07 10:05
    Originally posted by FischerRandom
    second and third are right but not the first.keep trying.
    Oh really? Because that's what maple gives me for the differential of arcsin(x+1/x) wrt x.
    Perhaps you meant arcsin((x+1)/x) or sin (x+1/x)^-1 or something else entirely.

    Keep trying.

    PS. These questions are stupid.
  6. 03 Jan '07 13:31
    Sorry - it's been a while since I did maths. Why doesn't the third exist?

    I am reading it as S (e^(x^2)) dx, maybe I'm wrong there? I can't see why that has no integral solution.
  7. Standard member XanthosNZ
    Cancerous Bus Crash
    03 Jan '07 13:45
    Originally posted by Zeddicus
    Sorry - it's been a while since I did maths. Why doesn't the third exist?

    I am reading it as S (e^(x^2)) dx, maybe I'm wrong there? I can't see why that has no integral solution.
    Try it.
  8. 03 Jan '07 13:51
    Originally posted by XanthosNZ
    Oh really? Because that's what maple gives me for the differential of arcsin(x+1/x) wrt x.
    Perhaps you meant arcsin((x+1)/x) or sin (x+1/x)^-1 or something else entirely.

    Keep trying.

    PS. These questions are stupid.
    Using maple? Well, then it is not hard...
    Using Fritz too?
  9. 03 Jan '07 14:00
    Lol, there's no way I can do it, but I don't take my inability to do something as proof that something can't be done! That would make mathematics far too easy.

    Is there a consise proof that it's not possible?
  10. Standard member XanthosNZ
    Cancerous Bus Crash
    03 Jan '07 14:03
    Originally posted by FabianFnas
    Using maple? Well, then it is not hard...
    Using Fritz too?
    If you don't want to use maple (or similar) you basically go to a big table of differentials and look it up.
    It's the same in the end and one is faster than the other.

    I'll assume that the last comment is a joke.
  11. 03 Jan '07 15:42
    Originally posted by XanthosNZ
    Oh really? Because that's what maple gives me for the differential of arcsin(x+1/x) wrt x.
    Perhaps you meant arcsin((x+1)/x) or sin (x+1/x)^-1 or something else entirely.

    Keep trying.

    PS. These questions are stupid.
    no i mean only sin inverse and nothing else.
  12. 03 Jan '07 17:09
    Originally posted by XanthosNZ
    If you don't want to use maple (or similar) you basically go to a big table of differentials and look it up.
    It's the same in the end and one is faster than the other.

    I'll assume that the last comment is a joke.
    Of course it was a joke, hence the blinking MrSmilie.
    But still, solving a mathematical puzzle using Maple doesn't give any credits, as solving a mate-in-two using Fritz...
    I don't think the threadmaker, the puzzlemaker, ment that the puzzle would be solved with silicon intelligence but with the more sofisticated computer, called brain.
    Now, before you get angry I put another MrSmiley to smooth any hard feelings:
  13. Subscriber BigDoggProblem
    The Advanced Mind
    03 Jan '07 17:38
    Originally posted by FabianFnas
    Of course it was a joke, hence the blinking MrSmilie.
    But still, solving a mathematical puzzle using Maple doesn't give any credits, as solving a mate-in-two using Fritz...
    I don't think the threadmaker, the puzzlemaker, ment that the puzzle would be solved with silicon intelligence but with the more sofisticated computer, called brain.
    Now, before you get angry I put another MrSmiley to smooth any hard feelings:
    How about solving a mate in 100+ moves with 2 Knights versus a Pawn? There are some of those in the Nalimov tablebase. What human would want to bother solving such a tedious and lengthy endgame?

    Puzzlemakers do not always intend for their puzzle to be solved by humans. See question 2 of the puzzle in Thread 56774.
  14. 03 Jan '07 18:27
    Originally posted by BigDoggProblem
    How about solving a mate in 100+ moves with 2 Knights versus a Pawn? There are some of those in the Nalimov tablebase. What human would want to bother solving such a tedious and lengthy endgame?

    Puzzlemakers do not always intend for their puzzle to be solved by humans. See question 2 of the puzzle in Thread 56774.
    True, but how hard can it be to press a button on a keyboard? If I solved a mate-in-99 with Fritz, does people say "Oh, how clever you are"? I don't think so.

    I know Xantoz is intelligent (no Smiley here) but even my nephew, 9 years old can press a button. Does this mean that he is clever as Xantoz? I don't think so.
  15. 03 Jan '07 19:14 / 4 edits
    Originally posted by FischerRandom
    no i mean only sin inverse and nothing else.
    If y = sin(x) then x = arcsin(y) or x = sin^-1(y)

    saying sin inverse (y) isn't very clear as it can be confused with

    x = 1 / sin(y) or x = sin(y)^1

    EDIT:

    1. The derivative of f(x) = arcsin x is given by

    f '(x) = 1 / sqrt(1 - x^2)

    Therefore the answer is

    1 / sqrt(1 - ((x^2 + x + 1) / x^2)

    Assuming you meant that sin inverse is arcsin.

    EDIT2: Which appears to be the same as Xanthos's answer, without doing any checking.

    Other edits were grammatical.