20. What is the derivative of f(x) = 2x3 -x2 + 4x - 8 a. 6x- - 2x + 4 b. 6x3 - 2x2 + 4x c. 6x- + 2x - 4 d. 6x3 + 2x3 - 4x 21. The function y = * - x + 5 is discontinuous at what point? a. 5 b. -5 c. 7 d. -7 22. On what values of x will make the function f(x) = x + 11 continuous. a. 11 b. -11 c. undefined d. all values of x 23. Which of the following is true for continuous functions? a. Continuous functions do not have graphs. b. Continuous functions are not differentiable. c. You can draw the graph of a continuous function with one single pen stroke without lifting it. d. You have lifted your pen once to draw the graph. 5x 24. Is the function defined by f (x) = 12x+3 ifx