(a) Find all the critical points of the function gm :9) = 1'3 + 481192 96:93 751' (5 marks) (b) For each critical point of 9, determine whether it is a local minimum, a local maximum, or a saddle point. (10 marks) (c) Find all the critical points of the function f(1.y) = 1'5 + y6 and determine whether there are a local minimum, a local maximum or a saddle point. ( 5 marks)