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!

Graphing a function

  1. Feb 4, 2013 #1
    1. The problem statement, all variables and given/known data

    I should sketch function (x^2 + x -12)/(x-4).




    3. The attempt at a solution
    I have problem with first derivative i find it to be (x^2 - 8x +8)/(x-4)^2 with roots at 4 - 2√2, 4 + 2√2, and 4(we lose four because f is not defined at 4). Where at 4 - 2√2 f is at max and at 4 + 2√2 f is at min. But when i plug those two roots in f i find that when x 4 - 2√2 f is = 3.32 and when i plug 4 + 2√2 i find f to be 16.47. How come min is greater then max? Is that even possible?
     
  2. jcsd
  3. Feb 4, 2013 #2

    Dick

    User Avatar
    Science Advisor
    Homework Helper

    Sure it is possible. They are only a local max and a local min. Start filling in your sketch of the rest of the function. You'll see what's happening.
     
  4. Feb 4, 2013 #3
    I figured it out by myself when i sketched graph. My professor didn't mention local max and min, he only talked about absolute. Thank you anyway.
     
  5. Feb 4, 2013 #4

    tiny-tim

    User Avatar
    Science Advisor
    Homework Helper

    Hi Government$! :smile:
    At x = 4 it goes off to infinity.

    The graph is effectively two unconnected graphs either side of x = 4, one with a maximum and one with a minimum …

    since they're unconnected, there's no reason why the maximum should be more than the minimum! :wink:
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook