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

Homework Help: Analysis: Limits, strictly increasing, differentiability

  1. Nov 16, 2011 #1
    I've worked all of these out. I'm mostly confident I did them correctly, but I'm prone to overlook subtleties or counterexamples sometimes.

    http://i111.photobucket.com/albums/n149/camarolt4z28/1ab-1.png [Broken]

    http://i111.photobucket.com/albums/n149/camarolt4z28/1gf2-1.png [Broken]
     
    Last edited by a moderator: May 5, 2017
  2. jcsd
  3. Nov 16, 2011 #2

    SammyS

    User Avatar
    Staff Emeritus
    Science Advisor
    Homework Helper
    Gold Member

    1. b is false.

    Is f(x) positive ?

    I'll look at the other problem soon.
     
  4. Nov 16, 2011 #3
    Oh. You're saying the limit could be negative infinity, too, not just positive infinity. That's true.
     
  5. Nov 16, 2011 #4

    SammyS

    User Avatar
    Staff Emeritus
    Science Advisor
    Homework Helper
    Gold Member

    Or, f(x) could alternate from large positive to large negative values as x → ∞.
     
  6. Nov 16, 2011 #5

    SammyS

    User Avatar
    Staff Emeritus
    Science Advisor
    Homework Helper
    Gold Member

    The second link looked OK to me.
     
  7. Nov 16, 2011 #6
    Good catch on (b). Thanks for the review!
     
  8. Nov 16, 2011 #7
    Its possible your professor wants you to write out your steps a bit more.
     
  9. Nov 16, 2011 #8
    For which ones?
     
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook