2. Consider the function f : R -> R defined by f(x) = x - cos(x). (a) Determine the intervals where f is concave up and concave down respectively. Make sure to indicate intervals of positive and negative sign for f"(x) on a number line. (b) Find all inflection points of f.3. Let C be the curve given by {(33, y) E R2 | 1:3 + 23:2 + my3 = 3?}. Find the :c-coordinates of the points on this curve with horizontal tangent lines (you may use the following information: there are at least two such points)