General ⇒ Alignment for a System of Equations

[mrmag]

Hello all,

how can I make left figure scope for the following system of inequalities?

Code: Select all

\begin{eqnarray}
4q+3  < 2q+6 \label{hello1} \\
4q-2q < 6-3   \label{hello2} \\
2q < 3           \label{hello3}
\end{eqnarray}

Thanks in advance!

[Stefan Kottwitz]

Hi mrmag,

welcome to the board!

Don't use eqnarray, this is an obsolete environment and could give inconsistent spacing, use the align environment of amsmath instead. For more explanation see: eqnarray vs. align.

This is your example inside align:

Code: Select all

\documentclass[a4paper,10pt]{article}
\usepackage{amsmath}
\begin{document}
\begin{align}
4q+3  &< 2q+6 \label{hello1} \\
4q-2q &< 6-3  \label{hello2} \\
2q    &< 3    \label{hello3}
\end{align}
\end{document}

I've chosen alignment on the inequality symbols.
What do you mean by "left figure scope"? Do you want all formulas left aligned? To each other or to the left margin?

Stefan

[mrmag]

Thanks for the prompt answer. I mean "{" - left figure scope. Each system should have such a scope. But I can't unite them together with the system...

[Stefan Kottwitz]

Like this?

Code: Select all

\documentclass[a4paper,10pt]{article}
\usepackage{amsmath}
\begin{document}
\[
\begin{cases}
  4q+3 < 2q+6 \\
  4q-2q < 6-3 \\
  2q < 3
\end{cases}
\]
\end{document}

Stefan

[mrmag]

Yes, like this. But the number of each row is disappeared! I need the system with the figure scope and numbers of inequalities?

[Stefan Kottwitz]

Then you could use the empheq package together with amsmath:

Code: Select all

\documentclass[a4paper,10pt]{article}
\usepackage{amsmath}
\usepackage{empheq}
\begin{document}
\begin{empheq}[left=\empheqlbrace]{align}
4q+3  &< 2q+6 \label{eq:1} \\
4q-2q &< 6-3  \label{eq:2} \\
2q    &< 3    \label{eq:3}
\end{empheq}
See \eqref{eq:1} and \eqref{eq:3}.
\end{document}

Here the equations will be aligned, numbered, they can be referenced and are grouped by a left brace.

Stefan

[mrmag]

This is the real solution of the problem! Thank you very much, Stefan!