Question

a rectangular storage area is to be constructed along the sides of a tall building. A security fence is required along the three remaining sides of the area. What is the maximum area that can be enclosed with 1000m fencing?

Answer 1

so one side is not needed.
let the two width be x m
let the one length be y m

2x + y = 1000
y = 1000 - 2x

area = xy
= x(1000-2x)
=1000x - 2x^2

d(area)/dx = 1000 - 4x
= 0 for a max of area
4x = 1000
x = 250
y = 1000-500 = 500

max area = xy
= 250(500)
= 125000 m^2

Answer 2

Reiny you are a Godsent Thanks Alot ^_^
Feeling more confident for finals now!

Answer 3

so is it a problem if I used dA/dx instead?