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!

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


    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
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Similar Discussions: Minimum and maximum of an equation
  1. Maximums and minimums (Replies: 7)

  2. Maximums and minimums (Replies: 5)

  3. Maximum And Minimum (Replies: 6)

  4. Maximums and Minimums (Replies: 6)

  5. Maximum and Minimum (Replies: 17)