Answer:
81 square feet
Step-by-step explanation:
Given the function
A(W) = 18w – [tex]w^{2}[/tex]
To find the greatest possible area the farmer can enclose in a rectangular pen
with 36 feet of fencing, we take the derivative on both sides of the function:
A'(w) = 18 -2w
=> A''(w) = -2
Since A"(w) is in negative, so the critical value will yield maximum value of the function.
So, A'(w) = 0
<=> 18 -2w = 0
<=> w = 9
Substitute w= 9 into the A(W) = 18w – [tex]w^{2}[/tex] , we have the greatest possible area is:
= 18*9 - [tex]9^{2}[/tex]
= 81 square feet