A rectangle is inscribed with its base on the x-axis and its upper corners on the parabola y=4−x^2. What are the dimensions of such a rectangle with the greatest possible area?

Question

A rectangle is inscribed with its base on the x-axis and its upper corners on the parabola y=4−x^2. What are the dimensions of such a rectangle with the greatest possible area?
Width =  
Height =

Steve · Answer

If the base has width 2x and height y, then the area is a = 2xy = 2x(4-x^2) so find x when da/dx =0