Minimum cost of an area of fencing using derivatives

In summary: Also, do not post images of text, please type your question directly. In summary, the task is to determine the dimensions of a rectangular garden that will be enclosed by fencing on all four sides, with the neighbor sharing the cost of one side. The homeowner wants to minimize their cost while still covering an area of 432 m^2. The cost per meter of fencing is $45, and the problem asks to find the individual costs for the homeowner and the neighbor.
  • #1
Physics345
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Homework Statement


A homeowner wishes to enclose a rectangular garden with fencing. The garden will be adjacent to his neighbour’s lot. There will be fencing on all four sides. His neighbour will be paying for half the shared fence.

a) What should the dimensions of the garden be if the area is 432 m^2 and the homeowner would like to keep his share of the cost to a minimum? Include a diagram.

b) At $45/m, what is the homeowner’s cost? What is the neighbor's cost?

Homework Equations

The Attempt at a Solution


For this question my main issue is the wording in the question I'm not sure exactly what it wants. Does it want me to find the homeowner/neighbors individual dimensions, or the dimensions of the whole garden.
Anyways here's what I've done so far let me know what you guys think.
Also on a side note, I wrote a whole bunch of stuff out on word, to ask about, so I'm just posting all of them at once on different threads (In case anyone was wondering about the multiple threads I just posted)

4fNUQBu.png
 

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  • #2
As I said in your other thread, your answer is hard to follow. It would help a lot if you typed your answer directly, see https://www.physicsforums.com/help/latexhelp/

Physics345 said:
For this question my main issue is the wording in the question I'm not sure exactly what it wants. Does it want me to find the homeowner/neighbors individual dimensions, or the dimensions of the whole garden.
I think that the problem is quite clear: "What should the dimensions of the garden be?" The answer should be the dimensions of the sides of the rectangle, with a specification as to which side is adjacent with the neighbour.

Your answer is correct.
 
  • #3
I need to stop doubting my self when I'm relatively sure the answer is correct. The doubt will go away with more practice hopefully.
Once again thank you!
 
  • #4
Thread moved. @Physics345, please post questions that involve derivatives in the Calculus & Beyond section, not in the Precalc section.
 

1. What is the minimum cost of fencing an area?

The minimum cost of fencing an area can be found using derivatives to optimize the function that represents the cost of fencing. This will give the lowest possible cost for a given area.

2. How do derivatives help in calculating the minimum cost of fencing?

Derivatives help in calculating the minimum cost of fencing by finding the critical points of the cost function. These points represent the minimum and maximum values of the function, and the minimum point will give the minimum cost for a given area.

3. What factors are considered in the cost function for fencing an area?

The cost function for fencing an area takes into account the length of the fence, the cost of materials, and the cost of labor. Other factors such as terrain and accessibility may also be included in the cost function.

4. Can the minimum cost of fencing be calculated without using derivatives?

While it is possible to find the minimum cost of fencing without using derivatives, it would be a more time-consuming and less accurate method. Derivatives provide a more efficient and precise way to optimize the cost function.

5. Are there any limitations to using derivatives in calculating the minimum cost of fencing?

Derivatives can only give an estimate of the minimum cost of fencing, as there may be other factors that cannot be accounted for in the cost function. These factors may include fluctuations in material prices and unforeseen obstacles during the fencing process.

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