A rectangular lot is bordered on one side by a stream and on the other 3 sides by 600m of fencing. The area is a maximum. Determine the area.

Answer 1

Let the width be x
let the length by y
2x + y = 600
y = 600-2x

Area = xy
= x(600-2x)
= 600x - 2x^2

If you know Calculus ...
d(area)/dx = 600 - 4x
= 0 for a max/min
4x = 600
x = 150
so Area = 150(600-300) = 45000 m^2

If you don't know calculus ...
complete the square ..
Area
= -2(x^2 - 300x + 22500 - 22500)
= -2((x - 150)^2 - 22500)
= -2(x-150)^2 + 45000

can you read the information from this last line ?

Answer 2

What are the three lengths the steps are unclear and seem unfinished