Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

I'm trying to show a function has non-uniform continuity

  1. Apr 2, 2008 #1
    I'm trying to show a function has non-uniform continuity, and I can't seem to think of 2 sequences (xn) and (yn) where |(xn) - (yn)| approaches zero, where f(x) = x3. Can anyone think of two sequences?
  2. jcsd
  3. Apr 3, 2008 #2
    Where are the two sequences x_n and y_n separately supposed to converge?
  4. Apr 3, 2008 #3
    |x_n - y_n| need to converge to 0.
    |f(x_n ) - f(y_n)| needs to converge to some real number, where f(x) = x^3
  5. Apr 3, 2008 #4
    I don't know if i am getting you right, but if there are no additional conditions imposed there, then i think the following would work

    [tex]x_n=\frac{1}{n}[/tex] [tex]y_n=\frac{1}{n^2}[/tex] these both converge to zero and also

    let [tex] |a_n=x_n-y_n=\frac{n-1}{n^{2}}|-->0, \ \ as \ \ n-->\infty[/tex]


    [tex]|f(x_n)-f(y_n)=\frac{1}{n^{3}}-\frac{1}{n^6}=\frac{n^3-1}{n^6}|-->0, \ \ as \ \ \ n-->\infty[/tex]
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook