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Homework Help: How do I find point D?

  1. Oct 25, 2011 #1
    1. The problem statement, all variables and given/known data

    The problem:

    [2] http://i.imgur.com/C5VwZ.png

    2. Relevant equations
    So I got the constraints to be

    1.x+y(less than or equal to) 275

    2.225x+250y (less than or equal to) 63,000

    3. x and y (Greater than) 0

    So if the line from point A is extrapolated, then where it hits the x axis would be constraint 2 and point C is constraint 1.

    3. The attempt at a solution

    The graph I ended up with:

    [1] http://i.imgur.com/9jJYt.png
    Last edited: Oct 25, 2011
  2. jcsd
  3. Oct 26, 2011 #2


    Staff: Mentor

    Point D is where the line x + y = 275 intersects with the line 225x + 250y = 63000. This is a simple matter of solving a system of two equations in two unknowns.

    The problem you posted in your first link seems to have nothing to do with what you're doing here.
  4. Oct 26, 2011 #3
    Whoops. Sorry about the wrong post.

    When I set the two equal to each other. -x + 275 = (225/250)x + (63000/250) I'm getting the incorrect answer.

    The book says it should be (230, 45)

    I keep getting (12.1, 262.9)
  5. Oct 26, 2011 #4


    Staff: Mentor

    You have a sign wrong in the right side. Solving the second equation for y gives y = -(225/250)x + 63000.

    I get the right answer.
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