Answer
(a) See graph.
(b) $-6i+10j$
(c) $2\sqrt {34}$
Work Step by Step
(a) Given $P(3,-1)$ and $Q(-3,9)$, we have $\vec u=\langle -3-3, 9+1 \rangle=\langle -6, 10 \rangle$ which is shown in the graph.
(b) We can express the above vector in terms of $i$ and $j$ as: $\vec u=-6i+10j$
(c) The length of $\vec u$ is given by $|\vec u|=\sqrt {(-6)^2+(10)^2}=2\sqrt {34}$
