Exercise 4.3.7

Now the 4 by 1 matrix in $Ax=b$ is $A={\left[\begin{array}{cccc}0\hfill & 1\hfill & 3\hfill & 4\hfill \end{array}\right]}^T$. Then $A^{T}A=[26]$ and $A^{T}b=[112]$. Best $D=112∕26=56∕13$.