9. The data shown in the Table below were collected in an experiment to optimize crystal growth as a function of three variables x1, x2, and x3. Large values of y (yield in grams) are desirable. Fit a second-order model and analyze the fitted surface. Under what set of conditions is maximum growth achieved? X1 X2 X3 66 -1 -1 -1 -1 -1 1 -1 1 -1 70 78 60 -1 1 1 1 -1 -1 80 1 -1 1 70 1 1 -1 100 1 1 1 75 -1.682 O o 100 1.682 o 0 80 o -1.682 0 68 o 1.682 0 O O -1.682 o O 1.682 82 63 65 o o 0 113 100 0 O o o O o 118 0 o o 88 o 0 0 100 o o o 85