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!

Differentiation math problem

  1. May 18, 2005 #1
    Quick question.

    To differentiate [tex]y = 20x (2x - 1)^6[/tex] I need to use the product rule:

    [tex] y = uv \ \Rightarrow \ \frac{dy}{dx} = v\frac{du}{dx} + u\frac{dv}{dx}[/tex]

    So that u = 20x and v = (2x-1)6

    However, do I differentiate v so that it equals 6(2x-1)5 or do I use:

    [tex]y = [f(x)]^n \ \Rightarrow \ \frac{dy}{dx} = n[f(x)]^{n-1} f'(x)[/tex]

    to give 12(2x-1)5???

    Cheers.

    The Bob (2004 ©)
     
    Last edited: May 18, 2005
  2. jcsd
  3. May 18, 2005 #2

    arildno

    User Avatar
    Science Advisor
    Homework Helper
    Gold Member
    Dearly Missed

    Why should it equal 6(2x-1)^5????
    You are to differentiate v with respect to "x", not with respect to "2x-1".
     
  4. May 18, 2005 #3
    Therefore it must be 12(2x-1)5???

    The Bob (2004 ©)
     
  5. May 18, 2005 #4

    arildno

    User Avatar
    Science Advisor
    Homework Helper
    Gold Member
    Dearly Missed

    Precisely, by the chain rule!
     
  6. May 18, 2005 #5
    Cheers.

    Sorry it seemed so trivial but I only started teaching myself tonight and the book I have sometimes misses some of the stages out e.g. I actually have v = (x-1)6 but this will come to 6(x-1)5 as the x-1 will become 1.

    Was simply checking.

    Appreciate the help.

    Cheers again. :biggrin:

    The Bob (2004 ©)
     
  7. May 18, 2005 #6

    dextercioby

    User Avatar
    Science Advisor
    Homework Helper

    It would be much easier to put Maple/other software to expand that bynomial make the multiplications and the then differentiate each term of the resulting sum.

    My guess...

    Daniel.
     
  8. May 18, 2005 #7

    arildno

    User Avatar
    Science Advisor
    Homework Helper
    Gold Member
    Dearly Missed

    Are you trying to bait me?
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?



Similar Discussions: Differentiation math problem
  1. Math problems? (Replies: 2)

  2. Math Problem (Replies: 2)

  3. Math problem (Replies: 3)

Loading...