[Tex/LaTex] Number equations and preserving alignment of equal signs

alignequationsline-numberingnumbering

So as I have learned from a previous post that the
\begin{aligned}…
\end{aligned} with the usage of "&" before "=" will help arrange neatly the equations where the equal sign of each equation will be just below the equal sign of the following equation and so on.

My question is if I have a total of 8 equations, how to number each equation and at the same time preserve the alignment of the equal signs.

Note if I use \begin{equation}… \end{equation}, I get only one number for the collection of 8 equations at the very end which is not what I want.

Best Answer

Here is a small sample of numbering equations.

\documentclass[12pt]{article}

\usepackage{amsmath}

\begin{document}

\begin{align} % numbers equations automatically
x &= (1-x) + 2x \\ % \\ ends the line
&= (x+y) - y \nonumber \\ % \nonumber removes the equation number 
&= \frac{x}{2} + \frac{x}{2} % last line does not have \\ 
\end{align}

\begin{align*} % use of * removes all numbers in this block
x &= (2x + 5) - (x+5) \\
&= yx - (y-1) x 
\end{align*}

\end{document}

This sample produces

Related Solutions

[Tex/LaTex] Aligning equations with two equal signs

To achieve this alignment, I would use \mathllap and \mathrlap, but I would use these in conjunction with the alignat environment, to ensure the proper alignment of = symbols on each line.

Example code:

\documentclass[a4paper]{article}
\usepackage{mathtools,amsmathm,amssymb}

\newcommand{\ddn}[2]{\frac{\mathrm{d}}{\mathrm{d}#1}#2}
\newcommand{\ddt}{\frac{\mathrm{d}}{\mathrm{d}t}}

\begin{document}
% Start an equation environment with two sets of aligned equalities
\begin{alignat}{2}
    x'(t) &=
    % RHS "overlaps" anything on its right (occupies no space to its right)
    \mathrlap{\ddt\left(
        \left[-\frac{M}{\omega^2}\cos{(\omega t)}+B_1\sin{(\omega t)}\right] + 
        \left[\frac{M}{\omega^2}-\frac{M}{T\omega^2}t\right]
    \right)}
    % Add a little bit of space on the RHS in the second set of equalities, for balance
    &&\mspace{120mu}
    % Start a new line of the equation but without adding any equation numbers
    \notag\\
    &= \frac{M}{\omega}\sin{(\omega t)}+B_1\omega\cos{(\omega t)}-\frac{M}{T \omega^2}
    % New line and equation number, with some added vertical space
    \\[1.5ex]
    \therefore x'(0) &=
    \frac{M}{\omega}\sin{(\omega 0)}+B_1\omega\cos{(\omega 0)}-\frac{M}{T \omega^2}
    % Second set of equalities
    &&= 0
    % New line and new equation number, with some added vertical space
    \\[1.5ex]
    % Align the new equation at the second set of equalities; LHS "overlaps" anything
    % on its left so that it doesn't push away the second `=' in the previous equation
    && \mathllap{\therefore B_1\omega-\frac{M}{T\omega^2}} &= 0
\end{alignat}
\end{document}

Example output:

Output for alignment at multiple ` symbols using the "alignat" environment

[Tex/LaTex] How to align multiple separate equations by equal sign to center of page

If you really want all the equality signs centered, consider

\documentclass{article}
\usepackage{mathtools}
\usepackage{lipsum}
\usepackage{tikz}% just for illustration
\begin{document}
\begin{equation}
\begin{split}
\mathllap{a} &= \mathrlap{b}\\
\mathllap{b} &= \mathrlap{c}
\end{split}
\end{equation}
\lipsum[1]
\begin{equation}
\begin{split}
\mathllap{foo} &= \mathrlap{x}\\
\mathllap{bar} &= \mathrlap{y}\\
\mathllap{baz} &= \mathrlap{z}
\end{split}
\end{equation}
\tikz[remember picture,overlay]{\draw[red](current page.north)--(current page.south);}
\end{document}

The TikZ and lipsum stuff are just for illustration.

And depending on how long "content" is, you may also use

\documentclass{article}
\usepackage{lipsum}
\usepackage{mathtools}
\begin{document}
\begin{align*}
a &= b\\
b &= c\\
\intertext{\lipsum[1]}
foo &= x\\
bar &= y\\
baz &= z
\end{align*}
\end{document}

Best Answer

Related Solutions

[Tex/LaTex] Aligning equations with two equal signs

[Tex/LaTex] How to align multiple separate equations by equal sign to center of page

Related Question