Deriving the Regression Equations Using Algebra

We can rewrite the denominator in the equations for a and b (which is the same as the expression for the determinant of the coefficient matrix of the system of linear equations (2) and (3)) as. 3(x1 2 + x2 2 + x3 2) - (x1 + x2 + x3)2. There is no solution when this quantity is zero. We expand to obtain ................
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