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!

Finding derivatives

  1. Jun 3, 2014 #1
    find the indicated derivative
    dp/dq if p = 1/(√q+1)

    I apologize ahead of time if you can't read my work.

    my work

    [(1/(√(q+h+1))) - (1/(√(q+1))] [itex]\div[/itex]h

    [((√(q+1)) - (√(q+h+1)))/((√(q+h+1))(√(q+1)))] [itex]\div[/itex]h

    [(q+1-q-h-1)/(((√q+h+1)(√q+1))((√q+1)+(√q+h+1)))][itex]\div[/itex] h

    [-h//(((√(q+h+1))(√(q+1)))((√(q+1))+(√(q+h+1))))][itex]\div[/itex] h

    -1//(((√(q+h+1))(√(q+1)))((√(q+1))+(√(q+h+1))))

    -1/[((√(q+1))(√(q+1)))((√(q+1))+(√(q+1)))]

    -1/[(q+1)(2√(q+1))] this was my answer


    the answer in the book is -1/[2(q+1)(√(q+1))]

    is my answer the same as the book or is there something else I still need to do?
     
    Last edited: Jun 3, 2014
  2. jcsd
  3. Jun 3, 2014 #2

    Ray Vickson

    User Avatar
    Science Advisor
    Homework Helper

    Do you mean
    [tex] p = \frac{1}{\sqrt{q+1}} \text{ or } p = \frac{1}{\sqrt{q} + 1}?[/tex]
    In text you should write the first as p = 1/√(q+1) and the second as p = 1/(1+√p) or 1/((√p)+1).
     
  4. Jun 3, 2014 #3
    I am sorry it is the first one [tex] p = \frac{1}{\sqrt{q+1}} [/tex]
     
  5. Jun 3, 2014 #4

    CAF123

    User Avatar
    Gold Member

    So your answer was $$-\frac{1}{(q+1)(2\sqrt{q+1})}$$ and the book's was $$-\frac{1}{2(q+1)(\sqrt{q+1})}?$$

    If so, yes they are the same. q is just a variable. It is the norm to see, for example, 2x rather than x2. And the latter becomes problematic when dealing with a product of different variables.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?
Draft saved Draft deleted



Similar Discussions: Finding derivatives
  1. Finding the Derivative (Replies: 11)

  2. Finding the derivative (Replies: 4)

  3. Find derivative (Replies: 1)

  4. Find the derivative. (Replies: 4)

  5. Find the Derivative (Replies: 12)

Loading...