Chapter 5.4, Problem 20E

By using paper and pencil, find the least-squares solution $\stackrel{\to }{x}*$ of the system
$A\stackrel{\to }{x}=\stackrel{\to }{b}$ , where $A=\left[\begin{array}{cc}1& 1\\ 1& 0\\ 0& 1\end{array}\right]$ and $\stackrel{\to }{b}=\left[\begin{array}{l}3\\ 3\\ 3\end{array}\right]$
Verify that the vector $\stackrel{\to }{b}-A\stackrel{\to }{x}*$ is perpendicular to theimage of A.