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

Homework Help: Easy derivative Q need help

  1. Nov 6, 2008 #1
    1. The problem statement, all variables and given/known data

    - 8 - sqr(29-4x+x^2)

    2. Relevant equations



    3. The attempt at a solution

    -8(-1/2)=4

    4(29-4x+x^2)^-1/2(2x-4)???

    am i on the right track?
     
  2. jcsd
  3. Nov 6, 2008 #2
    I'm no expert,
    if you have sqrt(u) you get 1/2sqrt(u)
    I don't think you can do the chain rule because you have -8-sqrt(u),
    so I think you have to take the derivative of -8 which is 0 - the derivative of sqrt(u).
     
  4. Nov 6, 2008 #3
    Remember that you can split up [tex]\frac{d}{dx}\left(-8-\sqrt{x^{2}-4x+29}\right)[/tex] to get [tex]\frac{d}{dx}\left(-8\right)-\frac{d}{dx}\left(\sqrt{x^{2}-4x+29}\right)[/tex]. From there you can apply the chain rule.
     
  5. Nov 7, 2008 #4

    HallsofIvy

    User Avatar
    Science Advisor

    You seem to have thought the -8 was MULTIPLYING the square root- it is not!
     
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook