How to insert Greek letters (having trouble with \greekletter)

This is my code:

\begin{equations}
\begin{align}
\lamba = \frac{x}{2}
\end{align}
\end{equations}


But \lamba appears just as a blank space.

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You seem to have several mistakes: \lamba = \lambda? it should be \begin-, not "equations", and why do you use align? – Peter Jansson Feb 24 '13 at 21:46
Welcome to TeX.sx! Please add a minimal working example (MWE) starting with \documentclass{...} and ending with \end{document} that illustrates your problem. And to add to @PeterJansson comment: Do not use the align environment inside another math-mode environment. align introduces math-mode on its own. – Qrrbrbirlbel Feb 25 '13 at 0:02

You would find comprehensive documentation online about typesetting equations. You can also Google for examples, you'll find several examples along with explanation. One such compilation is by Stefan M. Moser.

You would have to use the amsmath package.

To typeset inline equations, you may use the LaTeX shorthand $$...$$ or the Tex shorthand $...$. For numbered equations, you would have to use the equation environment. See below for examples:

\documentclass{article}
\usepackage{amsmath}

\begin{document}
We can use the \LaTeX~shorthand for inline equations such as $$\alpha = \beta + \gamma + \lambda$$.

For numbered equations we can use the \texttt{equation} environment.
$$\alpha = \beta + \gamma + \lambda$$

If we do not want the equations to be numbered, we may use the
\texttt{equation*} environment.
\begin{equation*}$$\alpha = \beta + \gamma + \lambda$$\end{equation*}

The \texttt{align} and/or \texttt{eqnarray} environment is used to group together multiple
equations and align them using \texttt{\&}
\begin{align}
\alpha &= \beta + \gamma * \lambda \\
\theta &= \frac{\alpha}{4}
\end{align}
\end{document}


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You should almost always avoid using eqnarray. See eqnarray vs. align. – Alan Munn Feb 25 '13 at 1:44