Answer:
The answer is below
Step-by-step explanation:
Let x represent the length of the rectangular pen and y represent the width of the rectangular pen. Since the total area of the pen is 169 ft², hence:
Area = length * width
169 = xy
y = 169/x
Also the perimeter of the rectangular pen is:
Perimeter (P) = 2(length + width)
P = 2(x + y)
P = 2x + 2y
P = 2x + 2(169/x)
P = 2x + 338/x
The least amount of fencing is at dP/dx = 0, hence:
dP/dx = 2 - 338/x² = 0
338/x² = 2
2x² = 338
x² = 169
x = 13 feet
y = 169 / x = 169/13 = 13 feet
The least amount of fencing = P = 2(x + y) = 2(13 + 13) = 52 feet
