A square sheet of cardboard measuring 40 cm on each side is to be converted into an open-top box by cutting out equal squares of side length x cm from each corner and folding up the resulting flaps.
(a) Express the volume V of the box as a function of x.
(b) Determine all critical values of V(x) that are feasible for the physical box.
(c) Identify the value of x that yields the maximum volume and calculate this maximum volume. Give both answers correct to two decimal places.
a. Part (a) -- model V(x)
b. Part (b) -- locate critical values
c. Part (c) -- select and evaluate the maximum