Suppose that f(x) is a function continuous for every value of x whose first derivative is f'(x) = = 2(1-x2) (1+x2)2 and f"(x) = 1x(x"-3) (1+x2)3 . Further, assume that it is known that f has a horizontal asymptote at y = 0. a. Determine all critical points of f. 2pts b. Find the intervals on which the graph of f is increasing or decreasing. 6pts c. Identify the x-values of all the local and absolute extrema. 4ptsd. Determine the intervals where f is concave up and concave down. e. Identify the x-value(s) of all inflection point(s). f. Sketch a possible graph of f (x)