! Missing } inserted. <inserted text> } l.84 \end {align}

Question

I am trying to code an equation into LaTeX but I keep getting this error. I found some similar questions, but the solutions given are also not working.

I'm working in a documentclass report. I also tried the code in article and book. I'm also using the package amsmath.

\begin{align}
\label{eqn:1}
$\Pi_W$  =  \large{$\frac {(c\rho)^c}{1 - \rho}$}\\
 \notag & = \large{$\frac {(c\rho)^c}{c!} \bigg( {(1-\rho)} \sum_{n=0}^{c-1} \frac {(c\rho)^n}{n!} + \frac {(c\rho)^c}{c!}$ \bigg) ^{-1}}
\end{align}

This is the equation I'm trying to get, beginning the second part. Also I only want the second line to have an equation number.

Note: I'm very new with LaTeX.

What did I do wrong?

Answer 1

There are two problems with that. In the first place, what are those $ signs doing there? In the second place, you cannot use \large in math mode.

This will compile without errors:

\documentclass{report}
\usepackage{amsmath}
\begin{document}
\begin{align}
\label{eqn:1}
\Pi_W  &=  \frac {(c\rho)^c}{1 - \rho}\\
 \notag & = \frac {(c\rho)^c}{c!} \bigg( {(1-\rho)} \sum_{n=0}^{c-1} \frac {(c\rho)^n}{n!} + \frac {(c\rho)^c}{c!} \bigg) ^{-1}
\end{align}
\end{document}

The next time, I suggest that you post a minimal working example.