Determine a cuboid with minimal surface area, if its volume is strictly greater than 1000, and the lengths of its sides are integer numbers.
(In reply to
Non-rectangular cuboids by Steve Herman)
Your thoughts seem to suggest generalizing this problem from a rectangular prism to a parallelepiped. We may not need to jump straight to calculus as there is a lot of linear algebra that can be used Specifically we are in R^3 and there is a lot of work that can be applied. But in any case definitely not D2 difficulty this problem is rated at.