Suppose that an experimenter uses the following design and wants to fit a second-degree polynomial model to the data using the method of least squares:
![1390_second-degree polynomial model.png](https://secure.tutorsglobe.com/CMSImages/1390_second-degree polynomial model.png)
(a) Write the 16 x 10 matrix of independent variables X.
(b) Is this a I near or nonlinear model?
(c) How many normal equations are there?
(d) What equation(s) would have to be solved to obtain the least squares estimate for β13?