# Why does \\ not return a new line in an equation?

\begin{equation*}\label{eq:pareto mle2}
A_0 = \frac{1}{(\alpha+t_x)^{r+s+x}}{}_2F_1\left(r+s+x,x+1;r+s+x+1;\frac{\alpha-\beta}{\alpha + t_x} \right ) "\\\" <br>
- \frac{1}{(\alpha+T)^{r+s+x}}{}_2F_1\left(r+s+x,x+1;r+s+x+1;\frac{\alpha-\beta}{\alpha + T} \right ),
\end{equation*}


This is my code why \\ does not go to new line? How should I make it?

The amsmath package -- which you appear to be loading already as your example code uses an environment called equation* -- provides quite a few environments to typeset equations that need to be split across two or more lines. The align* environment may be particularly suitable to the case at hand; note the use of & to state the alignment points.

\documentclass{article}
\usepackage{amsmath}
\begin{document}
\begin{align*}\label{eq:pareto mle2}
A_0 &=   \frac{1}{(\alpha+t_x)^{r+s+x}}{}_2 F_1\left( r+s+x,x+1;r+s+x+1;\frac{\alpha-\beta}{\alpha + t_x} \right)\\
&\quad - \frac{1}{(\alpha+T)^{r+s+x}}{}_2 F_1\left( r+s+x,x+1;r+s+x+1;\frac{\alpha-\beta}{\alpha + T} \right),
\end{align*}
\end{document}


Addendum: Note the close similarity of the outputs produced by the single align* environment in this answer and by the nested pair of equation*/multlined environments in @HarishKumar's answer.

• Good answer, thanks! Small detail: couldn't you get rid of the \quad by moving the& to immediately after the equal sign? – Janus Varmarken Nov 2 '18 at 20:33
• @JanusVarmarken - Thanks. The reason I used \quad to indent the second row was to follow a common typographic equation: to indicate visually that the second row is a continuation of the equation that began on the first row, the - symbol is deliberately not set immediately below the = symbol in the first row. – Mico Nov 2 '18 at 21:11
• oh, I think you misunderstood me - I completely agree that it should show up in that way. I'm just saying that you could avoid having to use \quad by moving the & of the first row so that you get A_0 =&. That way you still get the same output, but without having to include \quad in the second row. – Janus Varmarken Nov 2 '18 at 21:45
• @JanusVarmarken -- Look closely at the spacing around the = symbol if you write =& instead of &=: The spacing becomes highly asymmetric -- rather nonstandard! That's why the user guide of the amsmath package recommends writing &=. :-) – Mico Nov 2 '18 at 21:48
• ooh, I see - didn't notice that :). Thanks again! – Janus Varmarken Nov 3 '18 at 2:17

Both equation and equation* do not allow multi lined expressions. Use aligned from amsmath, inside equation* to break in to many lines. If alignment is not needed, you can use gathered (instead of aligned) as suggested by Mico.

\documentclass{article}
\usepackage{amsmath}
\begin{document}
\begin{equation*}\label{eq:pareto mle2}
\begin{aligned}
A_0 = \frac{1}{(\alpha+t_x)^{r+s+x}}{}_2F_1\left(r+s+x,x+1;r+s+x+1;\frac{\alpha-\beta}{\alpha + t_x} \right ) \\
- \frac{1}{(\alpha+T)^{r+s+x}}{}_2F_1\left(r+s+x,x+1;r+s+x+1;\frac{\alpha-\beta}{\alpha + T} \right ),
\end{aligned}
\end{equation*}
\end{document}


Or use multlined from mathtools:

\documentclass{article}
\usepackage{mathtools}
\begin{document}
\begin{equation*}\label{eq:pareto mle2}
\begin{multlined}
A_0 = \frac{1}{(\alpha+t_x)^{r+s+x}}{}_2F_1\left(r+s+x,x+1;r+s+x+1;\frac{\alpha-\beta}{\alpha + t_x} \right ) \\
- \frac{1}{(\alpha+T)^{r+s+x}}{}_2F_1\left(r+s+x,x+1;r+s+x+1;\frac{\alpha-\beta}{\alpha + T} \right ),
\end{multlined}
\end{equation*}
\end{document}


• Also split might be fruitful here, particularly with numbered equations. Of course, multlined is not needed, as multline* suffices. – egreg Aug 1 '14 at 9:34

There is an easy way to make \\ works in equation (change line):

$$a = b$$


Change it to

$$\begin{array}{l} a = \\ b \end{array}$$

• A side-effect -- possibly unpleasant -- of this approach is that the contents of the array environment will be processed in text-style math mode instead of in display-style math mode. – Mico Feb 21 '19 at 7:16

To obtain multi-lined expressions with equation number written beside, use the following code;

\documentclass{article}
\usepackage{mathtools}
\usepackage{amsmath}
\begin{document}
\label{eq:1} \begin{aligned} A_0 = \frac{1}{(\alpha+t_x)^{r+s+x}}{}_2F_1\left(r+s+x,x+1;r+s+x+1;\frac{\alpha-\beta}{\alpha + t_x} \right ) \\ - \frac{1}{(\alpha+T)^{r+s+x}}{}_2F_1\left(r+s+x,x+1;r+s+x+1;\frac{\alpha-\beta}{\alpha + T} \right ), \end{aligned}
\end{document}


• If you want to add the number at the last line of the equation, load the amsmath package with the option tbtags: \usepackage[tbtags]{amsmath} – Roland Deschain Jul 23 '19 at 11:49
• mathtools package inserts the amsmath package, so no need to call the package separately.... – MadyYuvi Oct 9 '19 at 5:36