Hello, I was given a 30-question worksheet on quadratic equation problems. I have about 4 questions I can't solve. I'll post up one for now. Help is greatly appreciated. Thank you!

Pizza Unlimited has the following prices for pizzas.

8 in. - $6

12 in. - $8.50

16 in. - $11.50

Is price a quadratic function of diameter? It probably should be, because the price should be proportional to the area, and the area is a quadratic function of the diameter. (The area of a circular region is given by $\displaystyle A=\pi r^2 or (\pi/4)*d^2.)$

a) Express price as a quadratic function of diameter using the data points (8,6), (12,8.50), and (16,11.50).

b) Use the function to find the price of a 14-in. pizza.

Thank you!