1. Not finding help here? Sign up for a free 30min tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Simple sup and inf questions

  1. Oct 11, 2013 #1
    find the sup and inf of the following sets:

    [tex] { x | x^2 - 5x + 6 < 0 } [/tex]

    I got the inf and sup to be 2 and 3 respectively

    [tex] { x^2 - 5x + 6 | x \in ℝ} [/tex]
    here I was rather confused what this is saying. I'm assuming it's taking about the graph x^2 - 5x + 6 and assumed this was between [-1/4, ∞] so inf = -1/4 and sup does not exist as it is not bounded from above.

    [tex] {x | x^2 + 1 = 0 } [/tex]
    as I'm in a real analysis class, there isn't a real number such that x^2 + 1 = 0, so inf and sup do not exist

    could anyone check my answers and if my reasoning is correct, especially for the second one please

    I don't understand why the curly brackets are not showing, but there should be curly brackets around all above in tex
     
  2. jcsd
  3. Oct 11, 2013 #2

    LCKurtz

    User Avatar
    Science Advisor
    Homework Helper
    Gold Member

    Looks good.

    It's talking about the range, so yes, that looks right too.

    The curly brackets have a special use in TeX, so to display then you use \{ and \} as I did editing your first set.
     
  4. Oct 11, 2013 #3
    thank you for a fast reply,

    is the last one correct too as you did not comment on that?
     
  5. Oct 11, 2013 #4

    LCKurtz

    User Avatar
    Science Advisor
    Homework Helper
    Gold Member

    I would say so as long as your text doesn't have some special convention for empty sets.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?
Draft saved Draft deleted



Similar Discussions: Simple sup and inf questions
  1. Lim inf/sup question (Replies: 6)

  2. Lim inf/sup question (Replies: 1)

  3. 3 part sup/inf question (Replies: 15)

Loading...