17. A variable Y was observed at 12 different combinations of values of controlled variables X1 and X2, with the results shown below. If the relation between Y and (X1, X2) may be assumed to be linear in the region covered by the choice of the 12 pairs (X1, X2), fit the regression model E(Y ) = β0 + β1X1 + β2X2 to these data.

X1 −2 −3 1 4 3 −2 −3 −1 −4 5 0 2 X2 0.5 −0.5 −0.5 1.5 −2.5 −4.5 2.5 −3.5 0.5 1.5 1.5 3.5 Y 15 11 17 18 23 11 17 13 14 32 21 24