An open topped box is to be made by cutting out identical squares from the corners of a rectangular piece of cardboard then folding up the resulting flaps. Thus, if the side of each removed square has length x then the box height will also be x. If the cardboard has dimensions 70cm by 50cm find an expression for the volume of the box V (x) in terms of x. What is the domain of this function? What sort of function is it (quadratic, cubic, rational or. . .)?