Let f(x) = |x² + 3x + 21. Graph f(x). Using the graphical evidence together with your conceptual knowledge of how f(x) should behave, answer the following questions, and explain your

answers. a) For what values of x, if any, is f(x) not defined? b) For what values of x, if any, is f(x) not continuous? c) For what values of x, if any, is f(x) not differentiable?