Answer
a. $4x(8-x)(12-x)$
b. $(0,8)$
Work Step by Step
a. Based on the given information, the three sides of the box are $x, 16-2x, 24-2x$; thus the volume is $V=x(16-2x)(24-2x)=4x(8-x)(12-x)\ in^3$
b. The domain of the above function can be found as $0\lt x\lt 8$ or $(0,8)$
