Note: If you are asked for value(s), give your answer as a single value (e.g. 17), or a comma separated list (e.g. 1,2,3), or NONE. If you are asked for an interval, give your answer in interval notation. Type INF for oo and -INF for -0. () Consider the function f(x) = x +4.5x2 - 12x - 1 and its derivatives: f'(x)=3x+9x - 12, f" (x)=6x+9. a) Determine the x-intervals on which f is concave up and concave down. f is concave up on: f is concave down on: b) What are the (x, y) coordinates of the inflection points of f? Enter your answer as an (x,y) coordinate, e.g. (91,-13), and separate multiple answers by commas.