Results 1 to 4 of 4

Math Help - How I can solve this question

  1. #1
    Senior Member
    Joined
    Oct 2009
    Posts
    290

    How I can solve this question

    Hiu

    How I can solve this question
    Attached Thumbnails Attached Thumbnails How I can solve this question-99.jpg  
    Follow Math Help Forum on Facebook and Google+

  2. #2
    -1
    e^(i*pi)'s Avatar
    Joined
    Feb 2009
    From
    West Midlands, England
    Posts
    3,053
    Thanks
    1
    Quote Originally Posted by r-soy View Post
    Hiu

    How I can solve this question
    To graph the equation between 0 and 5 start with the ordered point (0,100)

    You know that in 1 hour the amount will be 2^2 = 4 times the amount at 0 so you get the second ordered pair of (1,400)

    Plot the others similarly and draw the graph

    Spoiler:
    Use the exponential growth equation A_t = A_0e^{kt}

    We know that A_0 = 100 and that in t = \frac{1}{2} the number doubles - A_t = 2A_0 = 200

    Use this relationship to find the growth constant k

    200=100e^{\frac{1}{2}k}

    k = 2ln(2) = ln(4)

    Spoiler:
    A_t=A_0e^{t\,ln(4)} = A_0 \cdot 4^t



    As the graph is exponential growth I suggest using a log scale on the y axis

    ln(y)  = kt + ln(A_0) which gives a straight line in the form y=mx+c


    Edit: Plot ln(y) against t to get the straight line, with gradient k and y intercept ln(A_0)
    Follow Math Help Forum on Facebook and Google+

  3. #3
    Senior Member
    Joined
    Oct 2009
    Posts
    290
    thanks e^(i*pi)
    Follow Math Help Forum on Facebook and Google+

  4. #4
    MHF Contributor

    Joined
    Apr 2005
    Posts
    14,973
    Thanks
    1121
    There is no reason to use "e" or logarithms.

    There are 2N half hour periods in t hours so the population will have doubled 2t times: N= (100) (2^{2t})
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. How to solve this question with a ti-89
    Posted in the Pre-Calculus Forum
    Replies: 1
    Last Post: March 6th 2012, 11:31 AM
  2. How to solve this question ?
    Posted in the Algebra Forum
    Replies: 3
    Last Post: June 30th 2010, 11:19 AM
  3. help me solve the last question....
    Posted in the Math Software Forum
    Replies: 2
    Last Post: March 8th 2010, 07:18 PM
  4. ı can not solve the question
    Posted in the Statistics Forum
    Replies: 0
    Last Post: October 28th 2009, 04:47 AM
  5. Please solve my question
    Posted in the Pre-Calculus Forum
    Replies: 1
    Last Post: July 10th 2007, 09:37 AM

Search Tags


/mathhelpforum @mathhelpforum