An open-top box is made from a piece of card measuring 8cm by 6 cm with squares of side xcm cut out of the corners. a Find an expression for the volume of the open box in terms of x. b Plot a graph of V against x. c Find the x-intercepts. d State what the x-intercepts tell you about the possible range of values for x. e Find the local maximum and minimum values of V. f Explain why, in real life, V cannot be equal to one of the values you found in parte.