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!

Limitation first principle method

  1. May 28, 2012 #1
    1. The problem statement, all variables and given/known data
    Should be a simple question but its really tough for me because my lecturer had never teach me before about x^3

    Anyway, the question is find the first derivative by using first principle method :
    c) x^3+2x^2+1


    2. Relevant equations



    3. The attempt at a solution
    I did dy/dx = lim h->0 but during the process I am stuck because I am pretty confused about the expand part especially during the power for 3
     
  2. jcsd
  3. May 28, 2012 #2
    What do you mean by expanding for power 3? Assuming you want to expand (x+h)3, you need to multiply (x+h) thrice :wink: Or you can remember the result directly, or you can use the binomial theorem....

    Edit : Do show your work, it'll be easier to help you out then :smile:
     
    Last edited: May 28, 2012
  4. May 28, 2012 #3
    Yea, I meant by expanding the (x+h)3. I had managed to solve it using binomial theorem and it has saved me a lot of trouble. Thanks a lot Infinitum. Cheers :)
     
  5. May 28, 2012 #4
    You're welcome! :smile:


    On a side note,
    (a+b)3 is quite a commonly used identity, just like (a+b)2. It will surely help to memorize it.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook




Similar Discussions: Limitation first principle method
  1. The First Principles (Replies: 4)

  2. First principles (Replies: 5)

Loading...