\documentclass[a4paper,12pt]{article}
\begin{document}
\parindent=0pt

{\bf Question}

Find the work done by the force ${\bf F} = (4,3,2)$ in moving from
P$(-1,-2,4)$ to Q$(2,1,0)$

\vspace{.25in}

{\bf Answer}

$W = {\bf F} \cdot \vec{PQ} \hspace{.25in} {\bf F} = (4,3,2)$

$\vec{PQ} = \vec{OQ} - \vec{OP} = (2,1,0) - (-1, -2, 4) = (3, 3,
-4)$

${\bf F} \cdot \vec{PQ} = (4,3,2) \cdot (3,3,-4) = 12 + 6 - 8 = 13
= {\rm Work\ Done}$



\end{document}