Consider the following function. (If an answer does not exist, enter DNE.) ((X ) = x +9 X (a) Find the intervals where the function f is increasing and where it is decreasing. (Enter your answer using interval notation.) increasing decreasing (b) Find the relative extrema of f. relative maximum (x, y) = relative minimum ( x, y ) = (c) Find the intervals where the graph of f is concave upward and where it is concave downward. (Enter your answer using interval notation.) concave upward concave downward (d) Find the inflection points, if any, of f