Results 1 to 5 of 5

Math Help - Unknown Constants Possible Derivative Problem

  1. #1
    Member
    Joined
    Oct 2009
    Posts
    79

    Unknown Constants Possible Derivative Problem

    If h(x) = x^n / k and k is a nonzero constant and n is an integer, find the values of k and n so that where x=2, the value of h(x) is equal to 8 and the slope of the graph of the same function is -4

    Would i first solve the derivative and work from there? Thanks!
    Follow Math Help Forum on Facebook and Google+

  2. #2
    Super Member
    Joined
    Aug 2009
    From
    Israel
    Posts
    976
    Quote Originally Posted by r2d2 View Post
    If h(x) = x^n / k and k is a nonzero constant and n is an integer, find the values of k and n so that where x=2, the value of h(x) is equal to 8 and the slope of the graph of the same function is -4

    Would i first solve the derivative and work from there? Thanks!
    You will need to solve the following equation system:

    (1) \ h(2) = 8 \Rightarrow \frac{2^n}{k} = 8
    (2) \ h'(2) = -4

    So find the derivative, substitute it into the proper equation and solve for n,k.
    Follow Math Help Forum on Facebook and Google+

  3. #3
    Member
    Joined
    Oct 2009
    Posts
    79
    so would the derivative be h'(x)= (k)(nx^(n-1)) - x^n(1) / k^2
    Follow Math Help Forum on Facebook and Google+

  4. #4
    Super Member
    Joined
    Aug 2009
    From
    Israel
    Posts
    976
    Quote Originally Posted by r2d2 View Post
    so would the derivative be h'(x)= (k)(nx^(n-1)) - x^n(1) / k^2
    No. k is a constant, you don't treat it as a function of x.

    The derivative will be:

    h'(x) = \frac{nx^{n-1}}{k}
    Follow Math Help Forum on Facebook and Google+

  5. #5
    Member
    Joined
    Oct 2009
    Posts
    79
    Yup I solved this. Thank you for your help!!

    Thanks +1
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Variables and unknown constants?
    Posted in the Calculus Forum
    Replies: 3
    Last Post: July 31st 2011, 06:51 AM
  2. Replies: 3
    Last Post: April 15th 2011, 05:36 PM
  3. How to input data into maple with unknown constants?
    Posted in the Advanced Algebra Forum
    Replies: 7
    Last Post: February 8th 2011, 08:49 PM
  4. Finding unknown constants
    Posted in the Algebra Forum
    Replies: 6
    Last Post: January 7th 2011, 04:26 AM
  5. Replies: 1
    Last Post: April 4th 2009, 03:30 PM

Search Tags


/mathhelpforum @mathhelpforum