Problem 18. (6 points) NOTE: When using interval notation in WeBWork, remember that: You use 'INF' for oo and '-INF' for -co. And use 'U' for the union symbol. Enter DNE if an answer does not exist. f(x) = 2+6x2-4 a) Give the domain of f (in interval notation) b) Find the critical numbers of f. | (Separate multiple answers by commas.) c) Determine the intervals on which f is increasing and decreasing. f is increasing on: f is decreasing on: d) Use the First Derivative Test to determine whether each critical point is a relative maximum, minimum, or neither. Relative maxima occur at x = (Separate multiple answers by commas.) Relative minima occur at x = (Separate multiple answers by commas.) Note: You can earn partial credit on this problem. Move to Problem: 1 2 3 4 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 10 | 90