need help understanding

ll. Sketch the region bounded by the graphs of: f (K) = x4, 3" = l and then nd its area. llFindy'if y=f1t4t+9dt a 13. Sand falling 'Dl a hopper at lir 3fs forms a conical sand pile whose radius is always equal to its height. HG'W st is the radius increasing when the radius is 5 ft? 14. Calculate all critical points and inection points of f (1] = 4x5 5x4. Apply.r the second derivative test at each critical point. Show the correct concave structure and indicate the behavior off{x] as x 3- ion. 15. Find the open intervals on the xaxis on which the function flint] = x4 + 43:3 is increasing and those on which it is decreasing