13.2 Refer to Exercise 13.1.

a. Graph the relationship between E(Y) and x2 when x=0. Repeat for x = 1 and for x = 2.

b. What relationship do the lines in part a have to one another?

c. Suppose, in a practical situation, you want to model the relationship between E(Y) and two predictor variables x and x2. What is the implication of using the first-order model E(Y) = Bo+B1x1 + Bx2?