Chapter 3.CE, Problem 17CE

In exercises 13-23, give a brief answer.

Let $\left\{{\text{u}}_{\text{1}}\mathrm{.......}{\text{u}}_{\text{n}}\right\}$ be a linearly independent subset of $R^n$ and let $\text{x}$ in $R^n$ be such that ${\text{u}}_{\text{1}}{}^{\text{T}}\text{x}=\mathrm{.....}={\text{u}}_n{}^{\text{T}}\text{x}=\text{0}$. Show that $x=\theta$.