# White space and double align inside an align environment

I would like to vertically align two separate equations on the same line using the align environment. My code is given below.

\begin{align*}
3x&=4                           &&x=3 \\
x&=\frac{4}{3}
\end{align*}


While the two equations are vertically aligned, there is excessive white space between "or" and "x-3=0". Is it possible to remove this white space?

alignat lets you exercise more control over the horizontal space between the "columns" of equations than align does .

The following screenshot shows both the OP's align*-based solution and an alternative, alignat*-based solution.

\documentclass{article} % or some other suitable document class
\usepackage{amsmath}    % for 'align*' and 'alignat*' environments

\begin{document}

\texttt{align*}
\begin{align*}
3x&=4                         & x&=3 \\
x&=4/3
\end{align*}

\texttt{alignat*\{2\}}
\begin{alignat*}{2}
3x&=4 &                       x&=3 \\
x&=4/3
\end{alignat*}

\end{document}

• Thanks! Just one question: what does {.} next to \begin{alignat*} indicate ?
– Bell
Jan 25 at 5:39
• @Bell - To quote from p. 8 of the user guide of the amsmath package: "A variant environment alignat allows the horizontal space between equations to be explicitly specified. This environment takes one argument, the number of “equation columns” (the number of pairs of right-left aligned columns; the argument is the number of pairs): count the maximum number of &s in any row, add 1 and divide by 2." In short, since there are two "math columns" in the material at hand (and the maximal number of & symbols in any row is 3), the argument of alignat* has to be 2.
– Mico
Jan 25 at 5:47

It's easier to control such complicated alignments with IEEEeqnarray from IEEEtrantools.

\documentclass{article}
\usepackage{amsmath}
\usepackage{IEEEtrantools}

\begin{document}

\begin{IEEEeqnarray*}{l C r C l c r C l}
&          &   3x&=&4 &                       &   x&=&3 \\[1ex]
&          &    x&=&\frac{4}{3}
\end{IEEEeqnarray*}

\begin{IEEEeqnarray*}{l C c c c}
&          &   3x=4 &                       &   x=3 \\[1ex]
&          &    x=\frac{4}{3}
\end{IEEEeqnarray*}

\end{document}


I added a different realization that I like better, because it doesn't try to align unrelated equals signs.

You can do it also without IEEEtrantools.

\documentclass{article}
\usepackage{amsmath}
\usepackage{IEEEtrantools}

\begin{document}

\begin{equation*}
(3x+4)(x-3)=0 \implies
\begin{aligned}[t]
3x-4 &= 0 \\
3x &= 4 \\
x &= \frac{4}{3}
\end{aligned}
\begin{aligned}[t]
x-3 &= 0 \\
x &= 3
\end{aligned}
\end{equation*}

\begin{equation*}
(3x+4)(x-3)=0 \implies
\begin{gathered}[t]
3x-4 = 0 \\
3x = 4 \\
x = \frac{4}{3}
\end{gathered}