finding area and math

Question

A rancher has 4,740 feet of fencing available to enclose a rectangular area bordering a river. She wants to use part of the fencing to create a partition to separate her cows from her horses by dividing the enclosure into two equal areas as shown in the figure to the right. No fencing is required along the river. Let x represent the length of the center partition. Complete parts a. through d.

Answer 1

3x(4740-3x) = A = area

A'(x)= -018x + 3(4740)=0

x =3(4740)/18= 790 ft

4740-3x=4740-3(790)

= 4740-2370=2370 feet

790 by 2370 ft = max total area

2 areas are half that each

= 790 by 1185 ft