writing on multiple lines inside begin{align} ... end{align} environment

Question

Consider the result produced by:

\begin{align}
a & =  b + c + d \\
  & + e + f + g
\end{align}

I want a similar result when I put \left( and \right) such as:

\begin{align}
a & =  \left( b + c + d \\
  & + e + f + g \right) 
\end{align}

where \left( starts on first line and its brother \right) is on a different line.

how to achieve that? LaTeX is unable to connect \left( and \right) when they are on multiple lines.

EDIT: I want this because my actual equation is really long and has \left ( on the first line and \right ) on a different line.

which document class do you use and which packages do you use? ty :) — Mannie, Mar 24 '20 at 01:48
or you can just put a sample image or some clear visualization to understand your question. — Mannie, Mar 24 '20 at 01:59
Each cell of align and similar display environments is equivalent (for this purpose) to an \mbox -- \left and the matching \right must both be in the same "box", like the opening and closing of a group. You have them separated by &, which is not permitted. See Using \left( & \right) around amsmath's align delimiter (“&”) — barbara beeton, Mar 24 '20 at 02:02
If the fences will naturally be the same size in different cells, then the "unmatched" one can be matched by a period, as \left( ... \right. & \left. ... \right). But it's better to use a matching pair of the "big" modifiers, e.g. \bigl( ... & ... \bigr). This is pretty basic, so I recommend checking out some good basic documentation; see What are good learning resources for a LaTeX beginner? — barbara beeton, Mar 24 '20 at 03:06

0 Answers0