Could you please solve it step by step with clear explanation? Please do not only write the answer. Explanation is very important.

Question 2. (20 Marks) 0n Optimization without Constraints ((1) (10 Marks) Find the extreme value(s) of the following function with two variables under each case and determine if they are maxima or minima or saddle point: z=a$2+by2+c; Consider each of the following cases: (i)a > 0, b > 0, (ii)a