(+ 1 for comm.) Consider the function f(x) = x x2 + 4 , with first and second derivatives f(x) = 4 x2 (x2 + 4)2 and f (x) = 2x3 24x (x2 + 4)3 . (a) (2 points) Determine all vertical and horizontal asymptotes. (b) (3 points) Determine the intervals on which the function is increasing and decreasing. Classify all critical and singular points as either local minimums or maximums. (c) (3 points) Determine the intervals on which the function is concave up or down, and any inflection points. (d) (1 point) Sketch the graph of f(x).