Results 1 to 2 of 2

Math Help - Need help understanding what this question is asking.

  1. #1
    Junior Member ImaCowOK's Avatar
    Joined
    Aug 2010
    Posts
    33

    Need help understanding what this question is asking.

    The given function is:

    f(x) = \frac{5x}{4x+4}

    It's asking for f'(x) = \lim_{t \to x} and says the answer will involve the variables t and x.

    I found the derivative of the function using the Quotient Rule, but I don't understand the part where I need to take the limit which will include the variables t and x. Then it says taking the limit of that fractional expression gives f'(x) = _______. Wouldn't you have already found that in the first part of the question?
    Follow Math Help Forum on Facebook and Google+

  2. #2
    Flow Master
    mr fantastic's Avatar
    Joined
    Dec 2007
    From
    Zeitgeist
    Posts
    16,948
    Thanks
    5
    Quote Originally Posted by ImaCowOK View Post
    The given function is:

    f(x) = \frac{5x}{4x+4}

    It's asking for f'(x) = \lim_{t \to x} and says the answer will involve the variables t and x.

    I found the derivative of the function using the Quotient Rule, but I don't understand the part where I need to take the limit which will include the variables t and x. Then it says taking the limit of that fractional expression gives f'(x) = _______. Wouldn't you have already found that in the first part of the question?
    \displaystyle f'(x) = \lim_{t \to x} \frac{f(x) - f(t)}{x - t} is one of the standard 'differentiation from first principles' formulae.
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Replies: 2
    Last Post: December 1st 2011, 05:11 PM
  2. Understanding the contex of a question
    Posted in the Statistics Forum
    Replies: 1
    Last Post: September 25th 2011, 03:49 AM
  3. understanding this question
    Posted in the Discrete Math Forum
    Replies: 2
    Last Post: October 29th 2010, 10:06 AM
  4. Need help understanding this question
    Posted in the Calculus Forum
    Replies: 2
    Last Post: June 18th 2009, 09:44 AM
  5. A question about understanding f',f''
    Posted in the Calculus Forum
    Replies: 1
    Last Post: May 31st 2009, 06:35 PM

Search Tags


/mathhelpforum @mathhelpforum