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: Finding Derivitive of a Triangle Area

  1. Apr 11, 2012 #1
    My answer to this question seems close to that of the book but I have only solved for +1/2 and not the -1/2. Can anyone help?
    Many thanks.

    1. The problem statement, all variables and given/known data

    Q. The area of a triangle is [itex]\frac{-4m^2 + 4m - 1}{m}[/itex]. Find the value of m via differentiation.

    2. Relevant equations


    3. The attempt at a solution

    Attempt: [itex]\frac{dA}{dm}[/itex] = [itex]\frac{4m^2 - 4m - 1}{m^2}[/itex] = 0 => 4m2 - 4m + 1 = 0 => (2m - 1)(2m - 1) => m = 1/2

    Ans.: (From text book): [itex]\frac{dA}{dm}[/itex] = [itex]\frac{-4m^2 + 1}{m^2}[/itex] = 0 => m = +/- 1/2
    1. The problem statement, all variables and given/known data



    2. Relevant equations



    3. The attempt at a solution
     
  2. jcsd
  3. Apr 11, 2012 #2

    Pengwuino

    User Avatar
    Gold Member

    The question makes no sense and sounds incomplete. Find m by differentiation? That's not the derivative of A either. Are you sure you're not missing a portion of the problem?
     
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook