Answer
$2\sqrt {2}$
Work Step by Step
Component of $\textbf{u}$ along $\textbf{v}$= $\frac{\textbf{u}\cdot\textbf{v}}{||\textbf{v}||}$
$\textbf{u}\cdot\textbf{v}=⟨3,2,1⟩\cdot ⟨1,0,1⟩=3(1)+2(0)+1(1)=4$
$||\textbf{v}||=\sqrt {1^{2}+0^{2}+1^{2}}=\sqrt 2$
Therefore,
Component of $\textbf{u}$ along $\textbf{v}$ $=\frac{4}{\sqrt {2}}=2\sqrt {2}$