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Consider the following function. (If an answer does not exist, enter DNE.) f ( x ) = x+_ (a) Find the intervals where the function f is increasing and where it is decreasing. (Enter your answer 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 fis concave upward and where it is concave downward. (Ente concave upward concave downward (d) Find the inflection points, if any, of f