1. Not finding help here? Sign up for a free 30min 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!

Derivative question

  1. Oct 9, 2007 #1
    I forgot how to take these derivatives. Could someone tell me the rule/work it out.

    P = (doS1 + d1So) / (d1 + S1)

    dP/dS1 = ?

    I think it should be (denominator*d(numerator) - d(denom.)num.) / denom^2

    but that gets the wrong answer.
  2. jcsd
  3. Oct 9, 2007 #2


    User Avatar
    Staff Emeritus
    Science Advisor

    Are do and d1 constants? In other words, is this the same as
    [tex]P(x,y)= \frac{ax+ by}{b+ x}[/tex]?
    with z= do, b= d1, x= S1, y= So

    In that case, yes, the partial derivative of P with respect to x is "(denominator*d(numerator) - d(denom.)num.) / denom^2"
    (If So is also a constant, not a variable, then it is not a partial derivative but the same rule applies.)
  4. Oct 9, 2007 #3
    OK, but the d(denominator) with respect to S1 which is a variable is 1, right?
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?

Similar Discussions: Derivative question
  1. Derivative question (Replies: 11)

  2. Derivatives question (Replies: 2)

  3. Derivative question (Replies: 5)

  4. Derivative question (Replies: 1)

  5. Derivative question (Replies: 8)