Let f(x) = x3 48x. A: Give the domain of f. B: Find the critical numbers of f. C: Determine the maximal intervals on which f is increasing and decreasing. D: Use the First Derivative Test to determine whether each critical point is a relative maximum, minimum, ornehhen E: Find the possible points of inflection of f. F: Determine the intervals on which f is concave up or concave down