Please do 2 or 3 Let (x1, y1),..., (xn, Yn), n ≥ 2, be points on the R2 plane (each xi, Yi ER). We wish to find the straightline of "best fit" through these points ("best" in the sense that the average squared error is minimized);that is, we wish to find a, b E R to minimize1. Letf(a, b)=n1nXYX²Y2i=1(ax₂ + b - y₁) ².||||=||XY =BIH1-2n1-2*WI *WI=WI WI-WIXiYiXiyi.=Show that f(a, b) can be written in the form z¹Qz 2cTz + d, where z = [a, b]T, QCER² and dER, and find expressions for Q, c, and d in terms of X, Y, X², Y², XY.QTE R2X2.2. Assume that the ri, i = 1,...,n, are not all equal. Find the parameters a* and b* for the line ofbest fit in terms of X, Y, X², Y², XY. Show that the point (a*, b*) is the only local minimizer off. (Hint: X2_ (X)² = ²/²₁ (x₁ - x)².)12=3. Show that if a* and b* are the parameters of the line of best fit, then Y = a* X + b* (and hence oncewe have computed a*, we can compute b* using the formula b* =Y - a*X).

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2. Assume that the ri, i = 1,...,n, are not all equal. Find the parameters a* and b* for the line of best fit in terms of X, Y, X², Y², XY. Show that the point (a*, b*) is the only local minimizer of f. (Hint: X² - (X)² = ₁₁(x₁ - X)².) n 3. Show that if a* and b* are the parameters of the line of best fit, then Y = a*X+b* (and hence once we have computed a*, we can compute b* using the formula b* = Y - a*X).