Pre calculus mathematics

Question

the back of tom property is a creek .Tom would like to enclose a rectangular area using the creek as one side a d fencing for the other three sided to create a pasture. if there is 120 feet of fencing available what is the maximum possible area of the pasture?

Answer 1

Let x = length of the side parallel to the creek

y = length of each of the other two sides

Then, x + 2y = 120, so x = 120 - 2y

Area = A = xy = y(120-2y) = -2y² + 120y

maximum area when y = -120 / (2(-2)) = 30

So, y = 30ft and x = 60 ft