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!

The function f(x) = e^3x +6x^2 +1 has a horizontal tangent at x =?

  1. Feb 25, 2009 #1
    1. The problem statement, all variables and given/known data

    i cant solve it!
    im really lost. i know you find f''(x) (i got 9e^3x +12) but i dont know where to go from there
    what would i do on my calculator?
  2. jcsd
  3. Feb 25, 2009 #2
    to calculate the horizontal tangent you only need to solve for f ' (x) = 0. f '' (x) is used and further derivatives are used to check whether that particular solution of the first equation gives a maxima, minima or an inflexion point.

    Solve 3e^(3x) + 12x = 0
  4. Feb 26, 2009 #3


    User Avatar
    Science Advisor

    And that equation you will need to solve numerically, perhaps by graphing it on your graphing calculator and "zooming" in where it crosses the x-axis.
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook