Help with "Largest Area" of Rectangle Problem

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Discussion Overview

The discussion revolves around finding the largest area of a rectangle that has its base on the x-axis and its upper corners on the graph of the function f(x) = 16 - (x^2). Participants explore the mathematical approach to solving this optimization problem, including the use of derivatives and area formulas.

Discussion Character

  • Mathematical reasoning
  • Exploratory
  • Homework-related

Main Points Raised

  • One participant notes that f(x) is an upside-down parabola and suggests that the area A of the rectangle can be expressed as A = l(w), but expresses uncertainty about how to find the necessary points on the graph.
  • Another participant proposes taking a point (x,y) on the graph to derive the area function and suggests looking for similar examples in textbooks.
  • A question is raised about whether the area A(x) can be expressed as A(x) = x(16 - x^2) for 0 ≤ x ≤ 4, prompting further exploration of how this formulation can assist in finding the maximum area.
  • A hint is provided regarding the relationship between the height of the rectangle and the function f(x), suggesting that this can help express the area as a single-variable function of x.
  • A participant presents a calculation for the area, deriving the length L and height h, and arrives at a numerical value for the area, while questioning if they should multiply by 2 to account for the other side of the parabola.

Areas of Agreement / Disagreement

The discussion contains multiple viewpoints and approaches to the problem, with no consensus reached on the best method or final area calculation. Participants are exploring different aspects of the problem without agreeing on a single solution.

Contextual Notes

Some assumptions about the function and the rectangle's dimensions may not be fully articulated, and there are unresolved steps in the mathematical reasoning presented.

shadow5449
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Can anyone help me with this?

A rectangle has its base on the x-axis and its upper two corner on the graph f(x) = 16 - (x^2). What is the largest area the rectangle can have?
 
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What are your own thoughts on the matter?
 
Well, I know that the f(x) is going to be an upside down parabola. The area of a rectangle is obviously A = l(w). You would have to find the points on the graph to have your top line...but I'm not sure how you would do this. I'm thinking somthing with the derivative but that's where I'm stuck.
 
try taking a point (x,y) and generaly finding out what the area of the rectangle under will be. then, once you obtain that function, find its maximum. Try looking through your textbook for an example, since all of those kinds of problems are really the same.
 
Do you agree that the area A(x) of the rectangle is given by
[tex]A(x)=x(16-x^{2}),0\leq{x}\leq{4}[/tex] ?
How can this help you?
 
A slightly more specific hint:

any point on the graph of a function f(x) is (x,f(x)). Knowing that the corners of the rectangle are on the plot of the given function, what information can this give you about the height of the rectangle? How can this allow you to express A=lw as a single variable function of x?

I hope this helps.
 
A = L(h)
A = L(16 - L²)
A = 16L - L³
A` = 16 – 3L²

16 – 3L² = 0
√(L²) = √(16/3)
L = 2.3094011

h = (16 – 2.3094011²)
h = 10.6666

A = 24.63361146

Then I times it by 2 to account for the other side of the parabola (right?)
A = 49.26722297
 

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