4. We want to make an open-top box by cutting out corners of a square piece of cardboard and folding up the sides. The cardboard is a 9 inch by 9 inch square. The
volume V(x) in cubic inches of the open-top box is a function of the side length x in
inches of the square cutouts.

a) write an expression for V(x).

b) what is the volume of the box when x= 1?

c) what is a reasonable domain for V in this context?