f(x) = 13 -4.5x2 - 12x - 1 a) Find f'(x). b) Identify the graph that displays f in blue and f' in red. ? B. -5 c) Using the graphs of f and f', indicate where f is increasing and decreasing. Give your answer in the form of an interval. NOTE: When using interval notation in WeBWork, remember that: you use 'INF' for oo and '-INF' for -oo, and use 'U' for the union symbol. Enter DNE if an answer does not exist. f is increasing on f is decreasing on