Consider the graph of the function f (x) = x - x - 56. (a) Find the equation of the secant line joining the points (-6, -14), and (8, 0). (b) Use the Mean Value Theorem to determine a point c in the interval (=6, 8) such that the tangent line at c is parallel to the secant line. (c) Find the equation of the tangent line through c. (d) Use a graphing utility to graph f, the secant line, and the tangent line. 20- 20 12-20 -40 O O 20- (20- 40 -20 -40 20 20