Basic Mathematics - Old Questions

3. Define the concavity of the function. [2+3+3+2]

The graph of the function f(x) = x⁴ - 4x³ + 10 then
(i) Find the intervals on which f is increasing and on which f is decreasing. 
(ii) Find where the graph of f is concave up and where it is concave down. 
(iii) Find the local maximum or local minimum value of the function if they exist.