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!

Evaluating functions

  1. Oct 4, 2004 #1

    find L'(9)

    I think I need to use the product rule:


    Also, what if the question asked for f^3(x), how would I set that up?
  2. jcsd
  3. Oct 4, 2004 #2
    More generally if I let f(x) and g(x) denote two functions then the first derivative of their product, viz. g(x)f(x) is written as

    [tex]\frac{d[gf]}{dx} = g(x)\frac{df}{dx} + f(x)\frac{dg}{dx}[/tex]

    you seem to have applied the product rule correctly. I believe you mean f'(3) or f(x)^3. Is it so?

    You know that f(x = 9) = 3 and f'(x = 9) = -4. Do you think this information is sufficient to fix f'(x = 3) or f(x = 3)?
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?

Similar Discussions: Evaluating functions
  1. Evaluate the limit (Replies: 10)