[4] 3. Let f(x) = 4x 1. (a) Use the definition of the derivative to find f'(x). [2] (b) Find the equation of tangent line to f(x) at a = 5. [2] 4. Let f(x) { - 9 2(x-3) 2k+1 if x 3 if x = 3. (a) Show that f(x) is continuous for x 3. [3] (b) For what value of k is f(x) continuous at x = 3. [3] (c) Sketch the labeled graph of in the coordinate system below when k = 2. y x