Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Chain/Product rule

  1. Nov 4, 2006 #1
    I have a tricky derivative HW problem I'm working and am hoping someone might tell me if I'm doing this correctly or not. Thanks in advance!

    Find g'(x) where g(x) = [(1+4x)^5] X [(-x^2+x+3)^8)]

    By the product rule, I get:

    g'x = [(d/dx((1+4x)^5)) X (-x^2+x+3)^8] + [(d/dx(-x^2+x+3)^8) X (1+4x)^5)]

    Then, using the chain rule I get:

    g'(x) = [((d/dx((1+4x)^5))(d/dx(1+4x))) X (-x^2+x+3)^8] + [((d/dx((-x^2+x+3)^8))(d/dx(-x^2+x+3))) X ((1+4x)^5)]


    g'(x) = [(20(1+4x)^4) X (-x^2+x+3)^8] + [(8(-x^2+x+3)^7 X (-2x+1)) X ((1+4x)^5)]

    Then it should just be a matter of simplifying algebraically. Right?
    Last edited: Nov 4, 2006
  2. jcsd
  3. Nov 4, 2006 #2


    User Avatar
    Staff Emeritus
    Science Advisor
    Gold Member

    That's correct (even if it's a bit tough on the eyes :) )
  4. Nov 4, 2006 #3
    Thanks for looking over that mess for me. I'll have to get used to using LaTeX I suppose. :)
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook