The problems and results
Here is the standard calculus solution to Problem 1. Without loss of generality, assume
a ≤ b. We seek to maximize the volume
V (x ) = (a − 2x )(b − 2x )x = 4x
3
− (2a + 2b)x
2
+ abx (1)
for x ∈ [0,
a
2
]. The volume is zero at the endpoints, so the maximum volume must
occur for some value of x ∈ (0,
a
2
). To find the remaining critical points, we compute
V
0
(x ), set it equal to zero, solve for x , and check the results in V
00
(x ) to find that the
maximum volume comes from