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.

What are the length and width of the lot with the maximum area.
State the domain.
State the range

1 answer

length of single side parallel to stream ----- y m
length of each of the other two sides --- x m
2x+y=600
y = 600-2x

area = xy = x(600-x) = -x^2 + 600x

At this stage, I expect you to know how to find the vertex of this downwards parabola.
Either my using Calculus, completing the square or some other method.