Chapter 7, Problem 13SE

(a)

To determine

To show: that ${\text{x}}^{+}$ is in Row A.

(b)

To determine

To show: that the ${\text{x}}^{+}$ is a solution of $A\text{x}=\text{b}$.

(c)

To determine

To show: that “if u is any solution of $A\text{x}=\text{b}$, then $\Vert {\text{x}}^{+}\Vert \le \Vert \text{u}\Vert$, with equality only if $\text{u}={\text{x}}^{+}$”.