In Problems 15-22, find (a) $\mathbf{v} \times \mathbf{w},($ b) $\mathbf{w} \times \mathbf{v},(c) \mathbf{w} \times \mathbf{w}$, and (d) $\mathbf{v} \times \mathbf{v}$.
$\begin{aligned} & \mathbf{v}=-\mathbf{i}+3 \mathbf{j}+2 \mathbf{k} \\ & \mathbf{w}=3 \mathbf{i}-2 \mathbf{j}-\mathbf{k}\end{aligned}$