explanations, definitions , formulas used, graphs where applicable

Q2. Consider an individual whose utility function over quantities of X and Y takes the form: U = 100 - X2 _ y2 where U is an index of the individual's utility and X and Y are the weekly quantities of the two items consumed (for both items, quantities must be non-negative, so X 2 0 and Y 2 0). i. Are the indifference curves upward sloping or downward sloping? Are the indifference curves concave or convex? iii. Is X a 'good' or a 'bad'? iv . Is Y a 'good' or a 'bad'?Q3. Suppose the aggregate production function for a given economy is Q = AKaLB. i. What is the partial elasticity of Q with respect to K? ii. What is the proportionate differential of this function? Q4. What is the sum of the first 15 terms of the following series (rounded to the nearest 10 000)? 50000, 48500, 47000, 45500, ... ii. 100000, 50000, 25000, 12500