10. Let f(x) = 2x3-6r'. Determine the intervals over which f is increasing and those over which f is decreasing. Using the First Derivative test, find any local extreme values of f. Justify your answers. 11. Using the First Derivative Test, find any local extreme values of the function / from the previous problem. You may use the results of that problem. 12. Determine on which intervals the graph of the function f(a) = 2x* - 62' is concave up and those on which it is concave down. Justify your answer. 13. Using the results of the previous three problems, sketch the graph of f(a) = 2x3 - 62. 14. A farmer has 200 feet of fencing and wishes to construct two adjoining pens as shown below: What are the dimensions of the pen (length and width) that give the maximum area