A graphing calculator may NOT be used for the following problem. y + + X -3 -2 2 3 4 The figure above shows the graph of f', the derivative of a twice-differentiable function f, on the interval [-3, 4]. Answer the following questions based on the graph of f' a) Find all x-coordinates at which fhas critical values and identify them as a relative minimum, relative maximum, or neither. Justify your answer. b) On what open intervals contained in [-3, 4] is the graph of f both concave up and decreasing? Justify your answer. c) Find the x-coordinates of all points of inflection on the graph of f