Results 1 to 4 of 4

Math Help - Word problem help please...

  1. #1
    Member
    Joined
    Nov 2007
    Posts
    100

    Word problem help please...

    I need to solve this question by finding the maximum using differentiation. But word problems are my major weakness. I can't seem to construct an equation/graph based on the given data.

    The sum of two real numbers x and y is 12. Find the maximum value of their product xy.

    Help please...
    Follow Math Help Forum on Facebook and Google+

  2. #2
    Super Member
    Joined
    Jun 2008
    Posts
    792
    Given that:
    x+y = 12 \implies y = 12-x
    xy = k, for some value k.

    k = xy = x(12-x) = 12x - x^2

    \frac{dk}{dx} = 12 - 2x

    Can you continue?
    Follow Math Help Forum on Facebook and Google+

  3. #3
    Member
    Joined
    Nov 2007
    Posts
    100
    Alright, thank you. Solved the rest.

    Now another word problem that I cannot solve.

    A rectangular sheet of metal measures 50cm by 40cm. Equal squares of side x cm are cut from each corner and discarded. The sheet is then folded up to make a tray of depth x cm. What is the domain of possible values of x? Find the value of x which maximizes the capacity of the tray.
    Follow Math Help Forum on Facebook and Google+

  4. #4
    Super Member
    Joined
    Jun 2008
    Posts
    792
    No problem, glad to help.

    Please post new questions in new threads.
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. word problem - the snow plough problem?
    Posted in the Differential Equations Forum
    Replies: 1
    Last Post: October 13th 2011, 01:02 PM
  2. Replies: 3
    Last Post: January 2nd 2011, 08:20 PM
  3. 1 Word problem and 1 function problem
    Posted in the Algebra Forum
    Replies: 8
    Last Post: April 21st 2010, 08:01 AM
  4. Replies: 2
    Last Post: January 10th 2009, 05:49 AM

Search Tags


/mathhelpforum @mathhelpforum