Algebra Word Problem Help
posted by Katrina .
A gardener has 40 feet of fencing with which to enclose a garden adjacent to a long existing wall. The gardener will use the wall for one side and the available fencing for the remaining three sides.
If the sides perpendicular to the wall have length x feet, which of the following (A, B, C, or D) represents the area A of the garden? (No explanation required) Choice:
A. A(x) = –2x^2 + 20x
B. A(x) = –2x^2 + 40x
C. A(x) = 2x^2 – 40x
D. A(x) = x^2 – 40x
I say it's B
and based on that
The parabola opens down? agree or not?
Vertex = (10,200)??
The maximum area is 200 sqft?
When the sides perpendicular to the wall have length x = 10ft.
and the side parallel to the wall has length 20ft.
Is this all correct and accurate? Thanks!

Yes, that is still accurate.

Houston Community College is planning to construct a rectangular parking lot on land
bordered on one side by a highway. The plan is to use 640 ft of fencing to fence off the
other three sides. What should the dimensions of the lot be if the enclosed area is to be a
maximum?