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Ella Mental has $600$ ft of fencing to enclose two fields. One is to be a rectangle twice as long as it is wide and the other is to be a square. The square field must contain at least $100$ ft squared. The rectangular one must contain at least $800$ ft squared.

a. If $x$ is the width of the rectangular field, what is the domain of $x$?

b. Plot the graph of the total area contained in the two fields as a function of $x$.

c. What is the greatest area that can be contained in the two fields? Justify your answer

By the way, the answers to a, b, c are...(according to the textbook)

a. domain: $20\le x\le 93.333333\dots$

b. $A(x) = 22500 -450x + 4.25x$ squared

c. greatest area $= 17522.2222$

I keep getting the wrong answer for the greatest area. Please provide me with explanations to each

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    The maximum is obtained at one of the endpoints of the domain. (You need to check these as well as values at any critical points.)2012-08-09

3 Answers 3