Microeconomic Theory 11th Edition by Walter Nicholson,Christopher Snyder

Exercise 4

As we saw in Figure 3.5, one way to show convexity of indifference curves is to show that, for any two points (x 1 , y 1 ) and ( x 2 , y 2 ) on an indifference curve that promises U = k, the utility associated with the point
is at least as great as k. Use this approach to discuss the convexity of the indifference curves for the following three functions. Be sure to graph your results.
a. U(x, y) = min(x, y).
b. U(x, y) = max(x, y).
c. U(x, y) = x + y.
Reference: Figure 3.5