SOLUTION: Find the Maximum rectangular area that can be enclosed by a fence that is 224 m. Show your solution

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Question 1044337: Find the Maximum rectangular area that can be enclosed by a fence that is 224 m. Show your solution
Answer by ikleyn(52778) About Me  (Show Source):
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Find the Maximum rectangular area that can be enclosed by a fence that is 224 m. Show your solution
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Let x be the length of the rectangle and y be its width.

Then  x + y = 224%2F2 = 112,  and you are asked to find  x  and  y  in a way 
to maximize the product  x*y  which is the area.

Express  y  via  x:  y = 112 - x,  and substitute it into the product:

x*y = x*(112-x).

Now find the maximum of the quadratic function  f(x) = x*(112-x) = -x%5E2+%2B+112x.

The maximum is the vertex at x = -b%2F2a:

x = %28-112%29%2F%28-2%29 = 56.

So, x = 56 feet. Then y = 112-x = 56 feet too, and the rectangle is actually a square.