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!

Homework Help: Minimum and maximum of an equation

  1. Oct 24, 2008 #1
    The problem here is relatively simple...I just need to confirm something:

    A + B - C = D, in which B is a function of A and C is constant.
    dD/dA = 1 + dB/dA for the derivative
    To find a min/max of D for certain angles of A,
    dD/dA = 0 = 1 + dB/dA
    dB/dA = -1
    dB = -dA
    B = -A, which would imply that D is a min/max where B = -A and dB/dA = -1
    Dmin/max = A - A - C
    Dmin/max = -C, and thus D is a min/max where it is equivalent to -C.

    Was my mathematics wrong anywhere in there?
     
  2. jcsd
  3. Oct 24, 2008 #2

    Mark44

    Staff: Mentor

    Re: Maximum/Minimum

    If dB/dA = -1, then B = -A + a constant. IOW, the graph of B is a straight line with slope -1. Also, dD/dA = -A + a different constant.
     
  4. Oct 24, 2008 #3
    Re: Maximum/Minimum

    I see...thank you
     
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook




Loading...
Similar Threads for Minimum maximum equation Date
Minimum/Maximum problem Mar 15, 2018
Maximum/minimum problem Mar 11, 2018
Maximum-minimum area from a fixed length rope Nov 17, 2017
Local minimum and maximum Nov 14, 2017
Minimum-maximum problem with graph plotting Nov 3, 2017