Results 1 to 2 of 2

Math Help - easy function question ?

  1. #1
    Member
    Joined
    Sep 2008
    Posts
    239

    easy function question ?

    given that f(x) = e^x - x - 1, show that f is an increasing function for x>0


    OK i can see that this statement is true... but i just don't know how to write it on paper...
    Follow Math Help Forum on Facebook and Google+

  2. #2
    Junior Member
    Joined
    Jan 2009
    Posts
    36
    Quote Originally Posted by djmccabie View Post
    given that f(x) = e^x - x - 1, show that f is an increasing function for x>0


    OK i can see that this statement is true... but i just don't know how to write it on paper...

    Do you not just differentiate it, and show that is is > 0 on (1,\infty)??

    So f'(x) = e^x - 1

    e^x > 0 and  e^x > 1 for x > 0

    f'(x) > 0 for x>0

    Therefore

     f(x)  is an increasing function..


    Sound right?
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. easy function question
    Posted in the Algebra Forum
    Replies: 2
    Last Post: April 10th 2010, 11:48 PM
  2. Easy question about graphing a cos function
    Posted in the Calculators Forum
    Replies: 2
    Last Post: September 21st 2009, 06:09 PM
  3. Seemingly easy question... too easy.
    Posted in the Pre-Calculus Forum
    Replies: 3
    Last Post: August 23rd 2009, 10:36 PM
  4. easy, easy question
    Posted in the Discrete Math Forum
    Replies: 3
    Last Post: July 14th 2009, 08:38 AM
  5. Function question (easy but i dont understand)
    Posted in the Math Topics Forum
    Replies: 3
    Last Post: January 30th 2009, 10:00 PM

Search Tags


/mathhelpforum @mathhelpforum