"!Missing $ inserted" error using amsmath environments

Question

I am trying to compile a document with equations but whenever I use \begin{eqnarray}..\end{eqnarray} or \begin{align}...\end{align} or anything like this I get the error msg !Missing $ inserted.<inserted text>$. However if I type those equations without using \begin{eqnarray}...\end{eqnarray} or similar things I do not get any error msg and my document runs perfectly.

Even this simple thing does't work....Please help...

\documentclass[a4paper,12pt]{article}
\usepackage{amsmath}
\usepackage{amssymb}

\begin{document}

\begin{align}
$=$

\end{align}
\end{document}

align is automatically in math-mode. No need to enter it manually. Remove the $. — Qrrbrbirlbel, Aug 14 '13 at 18:03
It is rather the dollar symbols that you should delete; the align environment already switches to math mode; the $ are for inline math-mode. — Corentin, Aug 14 '13 at 18:04
even after deleting the symbol its showing the same error... — Misha, Aug 14 '13 at 18:05
all my equations are right indented.... how do i make them left indented??? — Misha, Aug 14 '13 at 18:21
Displayed equations are by default centered, if you want them pushed to the left, see http://tex.stackexchange.com/questions/54478/how-to-left-align-a-set-of-equations — Torbjørn T., Aug 14 '13 at 18:23
Since you have some responses below that seem to answer your question, please consider marking one of them as ‘Accepted’ by clicking on the tickmark below their vote count (see How do you accept an answer?). This shows which answer helped you most, and it assigns reputation points to the author of the answer (and to you!). It's part of this site's idea to identify good questions and answers through upvotes and acceptance of answers. — jub0bs, Aug 16 '13 at 11:32

score 11 · Accepted Answer · edited Apr 13 '17 at 12:35

Many of amsmath environments are already in math mode.

This applies to the environments

equation,
align,
gather,
flalgin,
alignat and
multline

as well as their starred (unnumbered) versions.

The environment split is to be used inside amsmath environments and can be used to split one equation on more than one line (this important for the equation number).

The environments

aligned,
gathered and
alignedat

are similar to the version without -ed but are to be used in math mode.

As pointed out in the comments by Torbjørn T. empty lines aren’t allowed in math mode, they trigger the same error message.

amsmath’s environments (those who actually enter math mode) center their contents horizontally. The align family aligns its content internally at every odd &. See the example below how they work. You can use the fleqn option so that amsmath align the whole content of its environment at the left border (with a certain margin).

Code

\documentclass{article}
\usepackage{amsmath}
\usepackage{showframe}
\begin{document}
\begin{equation}
c^2 = a^2 + b^2
\end{equation}

\begin{gather}
            c^2 = a^2 + b^2 \\
a^2 + 2ab + b^2 = (a + b)^2
\end{gather}

\begin{align}
\text{right-aligned} & \neq \text{left-aligned} \nonumber\\
                 c^2 & = a^2 + b^2 \\
     a^2 + 2ab + b^2 & = (a + b)^2
\end{align}

\begin{align}
            c^2 & = a^2 + b^2 \\
\begin{split}
a^2 + 2ab + b^2 & = (a + b)^2 \\
                & = (a + b)(a + b) \\
                & = aa + ab + ba + bb \\
                & = a^2 + 2ab + b^2
\end{split}
\end{align}
\end{document}

Output

enter image description here

"!Missing $ inserted" error using amsmath environments

1 Answers1

Code

Output

Linked

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