1. Limited time only! Sign up for a free 30min personal 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!

Find the supremum, infinum, maximum and minimum

  1. Aug 2, 2011 #1
    1. The problem statement, all variables and given/known data

    find the supremum, infinum, maximum and minimum
    2. Relevant equations
    (n-2sqrt(n)) n is element of natural numbers


    3. The attempt at a solution
    no idea on how to do this help please
     
  2. jcsd
  3. Aug 2, 2011 #2
    Re: sup,inf,max,min

    Drawing the graph is always a good idea. You know the graph of y=x and i assume also the graph of 2*x^1/2. After that you can easily sketch x-2*x^2 and then you'll probably have a better idea were to look
     
  4. Aug 2, 2011 #3

    Disconnected

    User Avatar
    Gold Member

    Re: sup,inf,max,min

    Do you know the definition of sup, inf, max and min, or is it just this question in particular that is causing problems?
     
  5. Aug 2, 2011 #4
    Re: sup,inf,max,min

    its this question in particular that's giving me the headache
     
  6. Aug 2, 2011 #5

    Disconnected

    User Avatar
    Gold Member

    Re: sup,inf,max,min

    Well, what is the smallest natural number? What is the value of the function at that point? Does the function increase or decrease from that point? Does it converse or diverge?
     
  7. Aug 2, 2011 #6
    Re: sup,inf,max,min

    Why don't you try finding the critical points for the related function [itex] f(x) = x - 2 \sqrt{x}[/itex] for real numbers and then restricting your answer to the naturals? This would also provide you with an easy way to use Disconnected's idea of examining when the function is increasing and decreasing.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook




Similar Discussions: Find the supremum, infinum, maximum and minimum
Loading...