Sophie knew her father well. He would be angry if he knew of her meeting with the young Irish footballer, Danny Casey. She did not tell him. When Geoff told his father about it, he became angry. He turned his head to look at her with disdain. Sophie wriggled where she was sitting at the table.
A carpenter needs to make a wooden cuboidal box, closed from all sides, which has a square base and fixed volume. Since he is short of the paint required to paint the box on completion, he wants the surface area to be minimum.
On the basis of the above information, answer the following questions :
Find \( \frac{dS}{dx} \).
