If the farmer has 250 feet of fencing to create a rectangular pen, define a function f that expresses the area of the field (measured in square feet) as a function of the width of the side of the field w (measured in feet). what is the maximum area possible?

Maximum area possible

f(max)  = 3906,25 ft²

Dimensions:

a  = 62,5  ft

w  = 62,5 ft

Step-by-step explanation:

Perimeter of the rectangular fencing    P  =  250 feet

And sides of the rectangle  a  and  w (width of rectangle)

Then

A =  a*w

2a  + 2w  = 250       ⇒  a  =  (250 -2w)/ 2    ⇒  a = 125 - w

f(w)  =  (125  - w ) *w        f(w)  = 125w - w²  

Taking derivatives both sides of the equation

f´(w)   =  125  - 2w              f´(w)   = 0           125  - 2w = 0

w = 125/2

w = 62,5 ft            ⇒  a = 125 - 62,5

a = 62,5 ft

f(max)  = ( 62,5)²

f(max)  = 3906,25 ft²