1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Area as a function of side w/ relation to cost

  1. Nov 4, 2012 #1
    1. The problem statement, all variables and given/known data
    A security fence is to be built around a rectangular parking lot. The front side of the fence costs $60 per meter and the other three sides cost $30 per meter. The total cost of the fence is budgeted to be $7500.

    Part a).

    Express the area of the lot enclosed by the fence as a function of the length 'x' of the side that cost $60 per meter.


    2. Relevant equations

    A=length*width


    3. The attempt at a solution
    I have scanned and uploaded my attempt/work onto imgur. here


    http://i.imgur.com/SDB9T.jpg


    I have attempted the solution, where I had simplified the equation in relation to the cost I am not entirely sure if after that I had solved for the correct variable ( either y or x), and did I input the equation into the right equation (Area of rectangle as a function of length x).

    Any help would be greatly appreciated. Is my attempt correct?

    *****also, confused when they ask for the area of the lot as a function of the length x. So essentially I only want variable "x" in my area equation?******
     
  2. jcsd
  3. Nov 4, 2012 #2

    Dick

    User Avatar
    Science Advisor
    Homework Helper

    You've almost got it. But I don't see why you think l=2x and w=2y? Length is x and width is y.
     
  4. Nov 4, 2012 #3
    What did I do wrong? Can I get a hint? So, I am inputting y=125-1.5x into A= length*w, as w right?
     
  5. Nov 4, 2012 #4

    Dick

    User Avatar
    Science Advisor
    Homework Helper

    In what you posted you said A=2x*2y. Not A=xy.
     
  6. Nov 4, 2012 #5
    So, aside form my mistake of A= 2x+2y, replaced with A=xy, my answer should be correct?
     
  7. Nov 4, 2012 #6

    Dick

    User Avatar
    Science Advisor
    Homework Helper

    If you work out A=xy, it should be fine.
     
  8. Nov 4, 2012 #7
    Ok, thanks!
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook




Similar Discussions: Area as a function of side w/ relation to cost
  1. Area as a function (Replies: 4)

  2. Function and relations (Replies: 2)

Loading...