Question

The back of Jake's property is a creek. Jake would like to enclose a rectangular area, using the creek as one side and fencing for the other three sides, to create a corral. If there is 10001000 feet of fencing available, what is the maximum possible area of the corral?

Answer 1

125000 square feet

Explanation:

Since there are only three sides of the rectangle, the perimeter of the fence is:

Let x and y be the sides of the rectangle, we are left with:

2 * x + y = 1000

solving for and:

y = 1000 - 2 * x

The area of the corral is:

A = x * y

replacing

A = x * (1000 - 2*x)

A = 1000 * x - 2*x^2

to find the maximum for the parabolic function A = 1000 * x - 2*x^2

The function has a maximum since the quotient before x ^ 2 is negative: -2 <0

Amax = c - b^2 /4*a

where a = -2, b = 1000, c = 0

A max = 0 - 1000^2/(4 * (- 2))

A max = 125000 ft^2

The maximum possible area of the pen is 125000 square feet.