1. 11 18
2. H α Journ. Chem. Soc.
3. \documentclass{article}\pagestyle{empty}\begin{document}$ \frac{{{\rm A}^2 - 1}}{{{\rm A}^2 + 2}} $\end{document} 2 \documentclass{article}\pagestyle{empty}\begin{document}$ \frac{{1 - 3}}{{1000}} $\end{document} 2 2 \documentclass{article}\pagestyle{empty}\begin{document}$ \frac{{6 - 1}}{{1000}} $\end{document} 2
4. 3 0 12 27