[-/20 Points] DETAILS 86. MY NOTES ASK YOUR TEACHER PRACTICE ANOT Use the graph of f' to identify the critical numbers of f, identify the open intervals on which f is increasing or decreasing, and determine whether f has a relative maximum, a relative minimum, or neither at each critical number. (If an answer does not exist, enter DNE.) (a) N f ' X -2 4 -2 -4 6 (i) Identify the critical numbers of f. (Enter your answers as a comma-separated list.) X = (ii) Identify the open interval(s) on which f is increasing or decreasing. (Enter your answer using interval notation.) increasing decreasing (iii) Determine whether f has a relative maximum, a relative minimum, or neither at each critical number. (Enter your answers as a comma-separated list.) relative minimum X = relative maximum X =