# Breaking equations within the align environment

I currently have these two equations, but they are too long to fit on one line:

\begin{align*}
[((a_0, a_1, a_2)+(b_0, b_1, b_2)) + (c_0, c_1, c_2)] &=
[((a_0 + b_0, a_1 + b_1, a_2 + b_2)) + (c_0, c_1, c_2)] \\
&= (a_0 + b_0 + c_0, a_1 + b_1 + c_1, a_2 + b_2 + c_2) \\
\end{align*}


I want to achieve something to this effect:

I have tried using the split environment within the align environment, but that doesn't allow me to align the line breaks, while also keeping the equal signs independently aligned. I am also open to alternative ideas on how to make this look better. (I do not think the second equality looks great in my mockup.)

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Welcome to TeX SX! Why do you want to break these equations? Each fits on a single line. – Bernard Jan 25 at 1:54
Welcome to TeX.SE. IMO, I think you should just begin the = on a subsequent line. – Peter Grill Jan 25 at 1:54
@Bernard The stuff after the equals sign goes into the margin. (I am doing this within an enumerate environment so that might cause it to go into the margin for me.) – user100000000000000 Jan 25 at 1:54
@PeterGrill Like this? i.imgur.com/RBc3Yzf.png – user100000000000000 Jan 25 at 1:57
It goes slightly into the margin, that is true, but doesn't if you load geometry, which defines more sensible margins than the default – unless you use marginal notes. If you don't, with the defaults of geometry, it's fits within text width. – Bernard Jan 25 at 2:03

Two more alternatives:

\documentclass[border=3mm,preview]{standalone}
\usepackage{mathtools}

\begin{document}
The first option:
\begin{align*}
[((a_0, a_1, a_2) + & (b_0, b_1, b_2)) + (c_0, c_1, c_2)]         \\
& = [((a_0 + b_0, a_1 + b_1, a_2 + b_2)) + (c_0, c_1, c_2)] \\
& = (  a_0 + b_0 + c_0, a_1 + b_1 + c_1, a_2 + b_2 + c_2)
\end{align*}
The second one:
\begin{align*}
[((a_0, a_1, a_2) + (b_0, b_1, b_2)) + (c_0, c_1, c_2)]
& = \begin{multlined}[t]
[((a_0 + b_0, a_1 + b_1, a_2 + b_2))\\
+ (c_0, c_1, c_2)]
\end{multlined}\\
& = \begin{multlined}[t]
(  a_0 + b_0 + c_0, a_1 + b_1 + c_1, \\
a_2 + b_2 + c_2)
\end{multlined}
\end{align*}
\end{document}


They gives:

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yet another possibility -- use aligned within multline:

\documentclass{article}
\usepackage{amsmath}
\begin{document}
\begin{multline*}
[((a_0, a_1, a_2)+(b_0, b_1, b_2)) + (c_0, c_1, c_2)] \\
\begin{aligned}
&= [((a_0 + b_0, a_1 + b_1, a_2 + b_2)) + (c_0, c_1, c_2)] \\
&= (a_0 + b_0 + c_0, a_1 + b_1 + c_1, a_2 + b_2 + c_2)
\end{aligned} \\
\end{multline*}
\end{document}


-

Try using eqnarray like this:

\begin{eqnarray}
[((a_0, a_1, a_2)+(b_0, b_1, b_2)) + (c_0, c_1, c_2)] & = &
[((a_0 + b_0, a_1 + b_1, a_2 + b_2))  \\
&   &              + (c_0, c_1, c_2)] \\
& = & (a_0 + b_0 + c_0, a_1 + b_1 + c_1, \\
&   & a_2 + b_2 + c_2) \\
\end{eqnarray}


you might need \nonumber to suppress equation numbering, since this it still pretty wide.

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For reference, see eqnarray vs align... – Werner Jan 25 at 4:49

I would suggest putting the = on its own line along with a \quad spacing before the =. To ensure that the first line does not effect the alignment use mathrlap.

Also, if you are using this within an enumerate list, then you can use aligned. This is assuming that there is not additional text before the math environment. Otherwise, use align*.

## Notes:

• There should not be a \\ in the last line of a display math environment.

## Code:

\documentclass{article}
\usepackage{mathtools}
\usepackage{enumitem}

\begin{document}
\begin{align*}
\mathrlap{[((a_0, a_1, a_2)+(b_0, b_1, b_2)) + (c_0, c_1, c_2)]} \\
&\quad= [((a_0 + b_0, a_1 + b_1, a_2 + b_2)) + (c_0, c_1, c_2)] \\
&\quad= (a_0 + b_0 + c_0, a_1 + b_1 + c_1, a_2 + b_2 + c_2) %\\  <--- No \\ on last line.
\end{align*}
Within an enumerate
\begin{enumerate}
\item
\begin{aligned}[t] \mathrlap{[((a_0, a_1, a_2)+(b_0, b_1, b_2)) + (c_0, c_1, c_2)]} \\ &\quad= [((a_0 + b_0, a_1 + b_1, a_2 + b_2)) + (c_0, c_1, c_2)] \\ &\quad= (a_0 + b_0 + c_0, a_1 + b_1 + c_1, a_2 + b_2 + c_2) %\\ <--- No \\ on last line. \end{aligned}
\end{enumerate}
\end{document}

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Here is a simple solution by manually inserting white space:

\begin{align*}
[((a_0, a_1, a_2)+(b_0, b_1, b_2)) + (c_0, c_1, c_2)] &=
[((a_0 + b_0, a_1 + b_1, a_2 + b_2)) \\
&~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + (c_0, c_1, c_2)] \\
&= (a_0 + b_0 + c_0, a_1 + b_1 + c_1,\\
&~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ a_2 + b_2 + c_2) \\
\end{align*}

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Welcome to TeX.SX! Wouldn't \hspace{<length>} be more convenient? – Torbjørn T. Jan 25 at 17:18

Here's a hack: introduce a new variable, like so:

We now compute the sum $S$ of our three vectors:
\begin{align*}
S&=[((a_0, a_1, a_2)+(b_0, b_1, b_2)) + (c_0, c_1, c_2)]\\
&=[((a_0 + b_0, a_1 + b_1, a_2 + b_2)) + (c_0, c_1, c_2)]\\
&=(a_0 + b_0 + c_0, a_1 + b_1 + c_1, a_2 + b_2 + c_2)
\end{align*}


This costs an extra line, but is well worth it in my opinion.

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