Outside of the United States, the common paper size is called A4 and measures 21 by 29.7 centimeters. Let V(x) = (21 - 2x)(29.7 - 2x)(x) be the volume in cubic centimeters of a
box made from A4 paper by cutting out squares of side length x in centimeters from each
corner and then folding up the sides.
What is a reasonable domain for V in this context? Explain or show your reasoning.