If 300 feet of fence are used to enclose a rectangular pen, the resulting area of the pen is A=150x-x^2, where x is the width of the pen.
a.What should the width be in order to have the max area?
b.What is the maximum possible area?
Hello,
to a.): You get the extreme value of A(x) if the first derivative of A equals zero.
Calculate A'(x).
Solve the equation A'(x) = 0 for x. (For confirmation only: x = 0 or x = 75)
to b.): Plug in the result from a.) into the given equation of the function. Determine which of the 2 values is the maximum (for confirmation only: $\displaystyle A_{max} = 5625$)