Results 1 to 6 of 6

Math Help - Another chain rule problem

  1. #1
    Member
    Joined
    Sep 2009
    Posts
    80

    Another chain rule problem

    Here it is:

    "Given y=f(x) with f(1)=4 and f'(1)=3, find

    (a) g'(1) if g(x)=sqrt(f(x))
    (b) h'(1) if h(x)=f(sqrt(x))"

    I've figured out (a), and the answer is 3/4. But I can't get (b).
    How do you solve it and what's the difference between the two annotations?
    Follow Math Help Forum on Facebook and Google+

  2. #2
    Super Member
    Joined
    Apr 2009
    From
    México
    Posts
    721
    h'(x)=\frac{f'(\sqrt{x} )}{2\sqrt{x} }
    Follow Math Help Forum on Facebook and Google+

  3. #3
    Member
    Joined
    Sep 2009
    Posts
    80
    Quote Originally Posted by Jose27 View Post
    h'(x)=\frac{f'(\sqrt{x} )}{2\sqrt{x} }
    Thank you. That's helpful.
    But what would f'(\sqrt{x}) be?
    Follow Math Help Forum on Facebook and Google+

  4. #4
    Super Member
    Joined
    Apr 2009
    From
    México
    Posts
    721
    I don't know exactly, but you're only asked to evaluate h'(1) and since \sqrt{1} =1 and you know the value of f'(1)...
    Follow Math Help Forum on Facebook and Google+

  5. #5
    Member
    Joined
    Sep 2009
    Posts
    80
    Wouldn't that just make it 3/4 again? But that's not right..
    Follow Math Help Forum on Facebook and Google+

  6. #6
    MHF Contributor
    skeeter's Avatar
    Joined
    Jun 2008
    From
    North Texas
    Posts
    11,701
    Thanks
    454
    Quote Originally Posted by Rumor View Post
    Wouldn't that just make it 3/4 again? But that's not right..
    h'(1) = \frac{f'(1)}{2\sqrt{1}} = \frac{3}{2}
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Chain rule problem
    Posted in the Calculus Forum
    Replies: 1
    Last Post: February 11th 2010, 01:06 AM
  2. chain rule problem
    Posted in the Calculus Forum
    Replies: 6
    Last Post: November 12th 2009, 07:04 PM
  3. Could use help on a Chain Rule problem
    Posted in the Calculus Forum
    Replies: 1
    Last Post: May 10th 2009, 08:05 PM
  4. chain rule problem
    Posted in the Calculus Forum
    Replies: 0
    Last Post: October 26th 2008, 08:42 AM
  5. Chain Rule Problem.
    Posted in the Calculus Forum
    Replies: 3
    Last Post: October 9th 2008, 10:31 PM

Search Tags


/mathhelpforum @mathhelpforum