The polynomial x 3 + 5x 2 -57x -189 expresses the volume, in cubic inches, of a shipping box, and the width is (x+3) in. If the width of the box is 15 in., what are the other two dimensions? ( Hint: The height is greater than the depth.)

Answer 1

the clue is that (x+3) divides the volume. So, a little checking shows that the volume

v = (x+3)(x-7)(x+9)
so, if x+3=15, x=12 and the box is 15x5x21