3D with Processing.. Catch Up Payments... noc-exa 4 Q of 6 D THINKING (14 marks) 19. Use the first or second derivative test (or both) to find the local maximum or minimum 4 points of f(x) = x - 8x + 18x 3 2 (4 marks) 20. A box with an open top is constructed from a rectangular piece of cardboard 2m x 3m by cutting a square from each of the four corners and bending up the sides. Determine the the dimensions of the box if it is to have a maximum volume. (6 marks)