Robert needs to fill up a box with packaging material. Use the picture below to calculate the volume of the box.
Length (2x+3)
Width (x+2)
Height (x-3)
volume = length x width x height
= (2x+3)(x+2)(x-3)
or, if it needs to be expanded ....
= (2x+3)(x^2 - x - 6)
= 2x^3 - 2x^2 - 12x + 3x^2 -3x - 18
= 2x^3 + x^2 - 15x -18