Chapter 8 - Polar Coordinates; Vectors - Section 8.6 Vectors in Space - 8.6 Assess Your Understanding - Page 645: 29

$2i+4j+k$

If a vector $v$ initiates at point $A(x_1,y_1,z_1)$ and terminates at $B(x_2,y_2,z_2)$, then we can write the vector as $v =\lt x_2-x_1, y_2-y_1, z_2-z_1 \gt =(x_2-x_1)i+(y_2-y_1)j+(z_2-z_1)k.$ Here, we have: $A=(3,2,-1)$ and $B=(5,6,0)$ Therefore, $v=(5-3)i+(6-2)j+(0-(-1))k\\ =2i+4j+k$