Consider the function f(x) = (a) The domain of f is x 7x-7 = x+3 (b) The horizontal asymptotes of f are y = (c) The vertical asymptotes of f are x = (d) Find all critical numbers c of f. C = (e) f is increasing for x (f) f is decreasing for x (g) f is concave up for x (h) f is concave down for x (i) The inflection points of occur at x = Note: Input U, infinity, and -infinity for union, , and -, respectively. If there are multiple answers, separate them by commas. If there is no answer, input none.