Results 1 to 9 of 9

Math Help - describe an instance when an inequality is impossible to solve..

  1. #1
    Super Member bigwave's Avatar
    Joined
    Nov 2009
    From
    honolulu
    Posts
    580

    describe an instance when an inequality is impossible to solve..

    Describe an instance when an inequality is impossible to solve..

    not sure how to answer this...
    Last edited by mr fantastic; December 23rd 2010 at 08:59 PM. Reason: Copied title into main body of post.
    Follow Math Help Forum on Facebook and Google+

  2. #2
    Flow Master
    mr fantastic's Avatar
    Joined
    Dec 2007
    From
    Zeitgeist
    Posts
    16,948
    Thanks
    5
    Quote Originally Posted by bigwave View Post
    Describe an instance when an inequality is impossible to solve..

    not sure how to answer this...
    x^2 < 0 is a simple example that comes to mind.

    (I assume the question wants you to think of an inequality that has no solution).
    Follow Math Help Forum on Facebook and Google+

  3. #3
    Banned
    Joined
    Dec 2010
    Posts
    19
    I don't see whats impossible about x^2<0, but this one may be:

    Continuum hypothesis - Wikipedia, the free encyclopedia
    Last edited by mr fantastic; December 25th 2010 at 05:48 PM. Reason: Restored deleted post. User banned.
    Follow Math Help Forum on Facebook and Google+

  4. #4
    MHF Contributor
    Prove It's Avatar
    Joined
    Aug 2008
    Posts
    11,492
    Thanks
    1393
    Quote Originally Posted by ark600 View Post
    I don't see whats impossible about x^2<0, but this one may be:

    Continuum hypothesis - Wikipedia, the free encyclopedia
    Because complex numbers can't be ordered...
    Follow Math Help Forum on Facebook and Google+

  5. #5
    Flow Master
    mr fantastic's Avatar
    Joined
    Dec 2007
    From
    Zeitgeist
    Posts
    16,948
    Thanks
    5
    Quote Originally Posted by ark600 View Post
    I don't see whats impossible about x^2<0, but this one may be:

    Continuum hypothesis - Wikipedia, the free encyclopedia
    The point is to provide help that is within the scope of what the OP is studying. Having reviewed the posting history of the OP, I concluded that the context of the question was real numbers - the impossibility of the inequality is obvious.

    If the context is complex numbers, then something like |z - 1| + |z + 1| < 2 will work.

    I very much doubt that the OP is at the level of understanding the content of the given link, which defeats the point of helping with the question.
    Follow Math Help Forum on Facebook and Google+

  6. #6
    Banned
    Joined
    Dec 2010
    Posts
    19
    Quote Originally Posted by Prove It View Post
    Because complex numbers can't be ordered...
    And so, the solution is that there is no solution.

    (Sorry MrFantastic, I didn't read your bit at the end in brackets- I assumed it was part of your signature- I ignore them.)
    Last edited by mr fantastic; December 25th 2010 at 05:47 PM. Reason: Restored deleted post. User banned.
    Follow Math Help Forum on Facebook and Google+

  7. #7
    Flow Master
    mr fantastic's Avatar
    Joined
    Dec 2007
    From
    Zeitgeist
    Posts
    16,948
    Thanks
    5
    Quote Originally Posted by Prove It View Post
    Because complex numbers can't be ordered...
    Thanks for your reply to ark600. However, although what you say is true, it's not relevant to the example I gave because x = i, for example, satisfies x^2 < 0.

    But usage of the pronumeral x (rather than z) implies real numbers, so I'd have thought that the impossibility of x^2 < 0 would be obvious. The OP seems to get it.
    Follow Math Help Forum on Facebook and Google+

  8. #8
    Super Member bigwave's Avatar
    Joined
    Nov 2009
    From
    honolulu
    Posts
    580

    Cool devation

    yes this question was in the algebra 1 level however it does have a section on imaginary numbers and I did also consider that as part of answer...

    but here is another question (I have a limit of 2 questions)
    Describe and draw the graph of the solution of all points that have a deviation less than 3 from the point (2, -1)

    I assume that word "deviation" would imply a circle 3 units in radius whose center is pt (2, -1) the "less than" would imply up to the circle but not including it.

    sorry but too temped to ask if a set of imaginary points can be restricted to the inside of circle. (this is not part of textbook question) I don't think it is but maybe it is.
    Follow Math Help Forum on Facebook and Google+

  9. #9
    MHF Contributor
    Prove It's Avatar
    Joined
    Aug 2008
    Posts
    11,492
    Thanks
    1393
    Quote Originally Posted by bigwave View Post
    yes this question was in the algebra 1 level however it does have a section on imaginary numbers and I did also consider that as part of answer...

    but here is another question (I have a limit of 2 questions)
    Describe and draw the graph of the solution of all points that have a deviation less than 3 from the point (2, -1)

    I assume that word "deviation" would imply a circle 3 units in radius whose center is pt (2, -1) the "less than" would imply up to the circle but not including it.

    sorry but too temped to ask if a set of imaginary points can be restricted to the inside of circle. (this is not part of textbook question) I don't think it is but maybe it is.
    I agree with you that it is a circle of radius 3, centred at (2, -1), filled in and with the circle as a broken curve.


    And yes, a set of imaginary points can be restricted to the inside of a circle. You would say that it is all \displaystyle z \in C such that \displaystyle |z| < r.
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Solve the inequality
    Posted in the Algebra Forum
    Replies: 3
    Last Post: March 21st 2011, 04:31 AM
  2. Replies: 5
    Last Post: August 10th 2010, 02:00 AM
  3. Replies: 8
    Last Post: May 8th 2010, 08:52 AM
  4. Is it possible to solve this inequality for n?
    Posted in the Calculus Forum
    Replies: 4
    Last Post: August 5th 2009, 11:22 AM
  5. How to solve an inequality?
    Posted in the Algebra Forum
    Replies: 1
    Last Post: June 30th 2008, 08:22 PM

Search Tags


/mathhelpforum @mathhelpforum