5. (30 points) Let y = 25 - 15x3. (a) Determine y' and y". (b) Determine intervals on which the function is increasing; determine intervals on which the function is decreasing. (c) Determine the coordinates of all relative maximum and relative minimum points. (d) Determine intervals on which the function is concave up; determine intervals on which the function is concave down; (e) Determine the coordinates of all inflection points. (f) With the aid of the information obtained in parts (a)-(e), give a reasonable sketch of the curve