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

  1. Feb 25, 2009 #1

    meredith

    User Avatar

    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?
     
    meredith, Feb 25, 2009
  2. jcsd
    Phys.org - latest science and technology news stories on Phys.org
  3. Feb 25, 2009 #2

    praharmitra

    User Avatar

    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
     
    praharmitra, Feb 25, 2009
  4. Feb 26, 2009 #3

    HallsofIvy

    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.
     
    HallsofIvy, Feb 26, 2009
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook