Consider the function 1 f (20 ) = 2 + 18x + 85 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. If the function does not have a relative maximum or minimum, type none. Relative maxima occur at x = (Separate multiple answers by commas.) Relative minima occur at x = (Separate multiple answers by commas.)