(a) Find the intervals on which f is increasing or decreasing. (b) Find the local maximum and minimum values of f. (c) Find the intervals of concavity and the inflection points 27. f 9. f(x) = X3-3x2-3x + 4 10. f(x) 2x3- 9x2 + 12x - 3 11. fx)-x* - 2x2 + 3 13. f(x) = sin x + cos x, 0 x 14. f(x) = cos2x-2 sinx, 0 28. S fo (a (b 2Ï 2Ï (c 15-17