Multiline equation group

From https://groups.google.com/d/msg/mathjax-users/KVU0k1JnYnM/mUrXNq166d8J

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I now have the equations in about half of the pages of Chapters I & II of http://www.ltas-vis.ulg.ac.be/cmsms/uploads/File/Lagrange_essai_3corps.pdf expressed in MathJax. There are several instances of multiline equation groups (e.g. on p.231), of a form roughly indicated below and better shown in a green box in a short HTML page http://www.merlyn.demon.co.uk/one-page.htm. The version in <one-page.htm> uses a three-row HTML Table, in which three TD elements contain MathJax. Is there a better way to do it? - and, if so, please give sufficient clues. Note - below, the three left braces should be one big brace.

        {  equation 1 containing several \frac
(A)     {  equation 2 containing several \frac
        {  equation 3 containing several \frac

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I'd recommend

\left\{
\begin{array}{l}
{d^2x \over dt^2}
     + ( {{A+B} \over r^2} + {C \over r''^2} ) x
     + C ( {1 \over r'^2} - {1 \over r''^2} ) x' = 0,\\
{d^2y \over dt^2}
     + ( {{A+B} \over r^2} + {C \over r''^2} ) y
     + C ( {1 \over r'^2} - {1 \over r''^2} ) y' = 0,\\
{d^2z \over dt^2}
     + ( {{A+B} \over r^2} + {C \over r''^2} ) z
     + C ( {1 \over r'^2} - {1 \over r''^2} ) z' = 0;
\end{array}
\right.

for your example from one-page.html

The \left\{ makes a stretchy brace on the left, and the \right. makes a matching delimiter that is blank (\left and \right must come in pairs). The \begin{array}{l} starts an array with one column that is left-justified, and it ends at \end{array}. The rows are separated by \\. (If you had more than one column, the entries in a row would be separated by &.)

See Carol Fisher's excellent list of macros and examples for more information on what macros are available in TeX and how to use them.

Davide

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