Minimum cost. From a tract of land, a developer plans to fence a rectangular region and
then divide it into two identical rectangular lots by putting a fence down the middle.
Suppose that the fence for the outside boundary costs per foot and the fence for the
middle costs per foot. If each lot contains square feet, find the dimensions of
each lot that yield the minimum cost for the fence.
A) Dimensions are 48.07 ft for the side parallel to the divider and 85.29 ft for the other
side.
B) Dimensions are 85.29 ft for the side parallel to the divider and 48.07 ft for the other
side.
C) Dimensions are 64.03 ft for the side parallel to the divider and 64.03 ft for the other
side.
D) Dimensions are 60.37 ft for the side parallel to the divider and 67.91 ft for the other
side.
E) Dimensions are 67.91 ft for the side parallel to the divider and 60.37 ft for the other
side.
Determine the open intervals on which the graph of is concave
downward or concave upward.
A) concave downward on
B) concave downward on ; concave upward on
C) concave upward on ; concave downward on
D) concave downward on ; concave upward on