Differential Equations and Linear Algebra (4th Edition)

Published by Pearson
ISBN 10: 0-32196-467-5
ISBN 13: 978-0-32196-467-0

Chapter 5 - Inner Product Spaces - 5.5 Chapter Review - Additional Problems - Page 377: 18

Answer

$y=-\frac{15}{37} x-\frac{12}{7}$

Work Step by Step

The matrices can be formed as: $A=\begin{bmatrix} -3 & 1 \\ -2& 1 \\ -1 & 1\\ 0 &1 \\ 2 & 1 \end{bmatrix}$ $x=\begin{bmatrix} a \\ b \end{bmatrix}$ $b=\begin{bmatrix} 1\\ 0\\ 1\\ -1 \\ -1 \end{bmatrix}$ Apply matrices to the least square solution: $x_0=(A^TA)^{-1}A^Tb$ $=(\begin{bmatrix} -3& -2& -1 & 0 &2 \\ 1 & 1 & 1 & 1 & 1 \end{bmatrix} \begin{bmatrix} -3 & 1 \\ -2& 1 \\ -1& 1\\ 0&1 \\ 2 & 1 \end{bmatrix})^{-1} \begin{bmatrix} -3& -2& -1 & 0 &2 \\ 1 & 1 & 1 & 1 & 1 \end{bmatrix} \begin{bmatrix} 1\\ 0 \\ 1\\ -1\\ -1 \end{bmatrix}$ $=\begin{bmatrix} 18 & -4\\ -4 & 5 \end{bmatrix}^{-1} \begin{bmatrix} -3& -2& -1 & 0 &2 \\ 1 & 1 & 1 & 1 & 1 \end{bmatrix} \begin{bmatrix} 1\\ 0 \\ 1\\ -1 \\ -1 \end{bmatrix}$ $=\frac{1}{74}\begin{bmatrix} 5 & 4\\ 4 & 18 \end{bmatrix} \begin{bmatrix} -3& -2& -1 & 0 &2 \\ 1 & 1 & 1 & 1 & 1 \end{bmatrix} \begin{bmatrix} 1\\ 0 \\ 1 \\ -1 \\ -1 \end{bmatrix}$ $=\frac{1}{74} \begin{bmatrix} -11& -6& -1 & 4 & 14 \\ 6 & 10 & 14 & 18 & 26 \end{bmatrix} \begin{bmatrix} 1\\ 0 \\ 1\\ -1 \\ -1 \end{bmatrix}$ $=\frac{1}{74}\begin{bmatrix} -30\\ -24 \end{bmatrix}$ $=\begin{bmatrix} -\frac{15}{37} \\ -\frac{12}{7} \end{bmatrix}$ The equation of the least squares line associated with the given set of data points is $y=-\frac{15}{37} x-\frac{12}{7}$
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