23 4 5 The figure above shows the graph of / , the derivative of a twice-differentiable function / on the interval [-3, 4]. Answer the following questions based on the graph of f . a) Find all x-coordinates at which has 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