Optimizing Area of a Rectangular Pen - House 2

Author:
James
This is the graph of the area of the pen that needs to be built in House 2. The independent variable is the length of the pen. What happens as you change the length of the pen to the total area that is enclosed? Based on the graph, what is the optimal area that can be enclosed by the pen? How do you know? What is the length of the pen that produces the optimal area? What is the width that produces the optimal area?