9. Find the critical points for the function f(x) = 12x - x . Include a diagram to support your answer. (five marks a. (2, 16) and (-2, -16) C. (2, -16) and (0, 0) b. (0, 0) and (1, 2) d. (2, 16) and (1, 11) 10. Find the critical points for the function f(x) = x - 3x + 1. Include a diagram to support your answer.(five marks a. (-1, 3) and (1, -1) c. (1, -1) and (2, 3) b. (0, 1) and (1, -1) d. (-1, 3) and (0, 1)