Use the Second Partials Test to verify that the formulas for a and b given in Theorem 13.18 yield a minimum.

Data from in Theorem 13.18

THEOREM 13.18 Least Squares Regression Line The least squares regression line for {(x, y), (x, y2),. ... (x, yn)} is given by f(x) = ax + b, where a n n n - - n n Xi i=1 i=1 n and b = n n - (x ax). Yi