F(r) = r2 + 5 at r = 0, r = 1, and r = 4, as in Exercise 6. Find the slope between r = 0 and r = 1, and the slope between r = 1 and r = 4.
Check that the above curves do not have constant slope by computing the slopes between the points indicated. Compare with the graphs in Exercises 5 and 6 in Section 1.2.