Chapter 13 - Vector Geometry - 13.2 Vectors in Three Dimensions - Exercises - Page 659: 29

$$ e_w =\left\langle\frac{4}{\sqrt{21}},-\frac{2}{\sqrt{21}},-\frac{1}{\sqrt{21}} \right\rangle.$$

$$ e_w=\frac{w}{\|w\|}=\frac{\langle 4,-2,-1 \rangle }{\sqrt{16+4+1}}\\ =\left\langle\frac{4}{\sqrt{21}},-\frac{2}{\sqrt{21}},-\frac{1}{\sqrt{21}} \right\rangle.$$