Results 1 to 2 of 2

Math Help - log equations from graphs.

  1. #1
    Senior Member
    Joined
    Jul 2010
    Posts
    477
    Thanks
    5

    log equations from graphs.

    Hi; how do you find logarithmic equations from their graphs? Thanks.
    Follow Math Help Forum on Facebook and Google+

  2. #2
    MHF Contributor ebaines's Avatar
    Joined
    Jun 2008
    From
    Illinois
    Posts
    1,249
    Thanks
    380

    Re: log equations from graphs.

    I assume what you mean is: how do you interpret a plot on log-log paper? Given the equation y = Ax^k, take the log of both sides and rearrange to get:

    log(y) = k log(x) + log(A)

    Let Y= log(y) and X = log(x), and the plot on log-log paper will be:

    Y = kX + log(A)

    This is an equation of a straight line, with slope = k and Y-intercept for X=0 (i.e. x = 1) of log(A). Hence you can read the value of A directly off the graph for x=1.
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Graphs of Linear Equations
    Posted in the Algebra Forum
    Replies: 4
    Last Post: October 4th 2011, 11:20 AM
  2. Equations for the following graphs
    Posted in the Calculus Forum
    Replies: 3
    Last Post: August 2nd 2010, 05:55 AM
  3. Parametric Equations graphs
    Posted in the Calculus Forum
    Replies: 9
    Last Post: December 2nd 2009, 09:10 PM
  4. Graphs and equations
    Posted in the Pre-Calculus Forum
    Replies: 1
    Last Post: February 12th 2009, 11:40 AM
  5. Graphs of functions: Equations
    Posted in the Pre-Calculus Forum
    Replies: 1
    Last Post: October 17th 2008, 08:29 AM

Search Tags


/mathhelpforum @mathhelpforum