61 Consider the following quadratic models:

(1) y = 1 - 2x + x2

(2) y = 1 + 2x + x2

(3) y = 1 + x2

(4) y = 1 - x2

(5) y = 1 + 3x2

a. Graph each of these quadratic models, side by side, on the same sheet of graph paper.

b. What effect does the first-order term (2 x ) have on the graph of the curve?

c. What effect does the second-order term (x2) have on the graph of the curve?