1. Limited time only! Sign up for a free 30min personal 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!

Homework Help: Calculus problem, I don't understand what it means?

  1. Aug 17, 2008 #1
    1. The problem statement, all variables and given/known data


    2. Relevant equations


    3. The attempt at a solution

    Basically, I am in Physics C and this is our first homework assignment dealing with calculus/derivatives. I was able to do some of them, but I have no idea how to do this one, mainly because I don't know what to do with the Dx.

    To make sure I am on the right track, please tell me if this is the correct answer for another problem:

    Problem: f(x) = -5x2+2x-1, find df/dx

    And my answer is -10x + 2, using the power rule. Is that right?
  2. jcsd
  3. Aug 17, 2008 #2


    User Avatar
    Science Advisor
    Homework Helper

    … power rules ok!

    Hi dominus96! :smile:
    Completely! :biggrin:
    Dx is just another way of writing d/dx.

    Just use the power rule again … which, as you say, is:
  4. Aug 17, 2008 #3
    Thank you very much tiny-tim. If you don't mind, I have one more similar problem that is also written in a way I don't understand. Here it is:

    Find f' for f(x) = 11x - 2.

    Is f' (f prime) basically the first derivative again, or different?
  5. Aug 17, 2008 #4


    User Avatar
    Science Advisor
    Homework Helper

    Yup … same thing! :biggrin:

    (the advantage of the ' notation is that it's much easier to type f'' and f''' and so on! :smile:)
  6. Aug 17, 2008 #5


    User Avatar
    Science Advisor

    You should also remember that the derivative of a function, whether it is called "Dx f" or "df/dx" or "f' " is a generalization of the slope of a line- and since f(x)= 11x- 2 has a straight line as its graph, the derivative is ...
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook