4. Let f be the function given by f (x) = (x2 - 2x - 1)et. (a) Find lim f (x) and lim f(x). X-+00 *+-00 lim f(x) = X-900 lim f(x) = x-4-00 (b) Find the intervals on which f is increasing. Show the analysis that leads to your answer. c) Find the intervals on which the graph of f is concave down. Show the analysis that leads to your