Answer
$\sqrt {33}; \lt \dfrac{8}{\sqrt {33}},\dfrac{-2}{\sqrt {33}},\dfrac{8}{\sqrt {33}}\gt$
Work Step by Step
Here, $|v|=\sqrt{(4)^2+(-1)^2+(4)^2}=\sqrt {33}$
The unit vector $\hat{\textbf{u}}$ can be calculated as: $\hat{\textbf{u}}=\dfrac{v}{|v|}$
Now, $2 \hat{\textbf{u}}=2 [\dfrac{\lt 4,-1,4 \gt}{\sqrt {33}}]= \lt \dfrac{8}{\sqrt {33}},\dfrac{-2}{\sqrt {33}},\dfrac{8}{\sqrt {33}}\gt$
Thus, our final answers are: $\sqrt {33}; \lt \dfrac{8}{\sqrt {33}},\dfrac{-2}{\sqrt {33}},\dfrac{8}{\sqrt {33}}\gt$
