# Box Up The Cubic

Calculus Level 5

For a certain value $$p$$, there can be only one box that is tangent on all 4 sides to this cubic $${ x }^{ 3 }-px$$. Find the ratio of its sides. (The ratio is a number greater than 1.)

The box is a rectangle, possibly tilted. The cubic curve may pass through the box, but this cubic curve must nevertheless be tangential to all four sides of the box.