Let , where is given in the figure below.

(Click on the graph for a larger version.)

Find each of the following:



C. The interval (with endpoints given to the nearest 0.25) where is concave up:
interval =
(Give your answer as an interval or a list of intervals, e.g., (-infinity,8] or (1,5),(7,10), or enter none for no intervals.)

D. The value of where takes its maximum on the interval .