You can also visit the ShareLaTeX site. The left column has many useful links, especially under "Mathematics."
{\bf This is important.}
\usepackage{setspace} \doublespacing
$ u(x, y) = xy $.For equations that are on their own lines, enclose the equation in double dollar signs or \[ and \]. For example,
$$ u(x, y) = xy $$ or \[ u(x, y) = xy. \]
For automatically numbered equations that are on their own lines, enclose the equation in \begin{equation} and \end{equation}. For example,
\begin{equation} u(x, y) = xy. \end{equation}For equations that are on their own lines but are not numbered, you can also use \nonumber as follows:
\begin{equation} u(x, y) = xy. \nonumber \end{equation}For equations that are larger within a paragraph, use \displaystyle. For example,
${\displaystyle \frac{1}{2x}}$.
To exponentiate, use the caret symbol. If the expression in the exponent is more than a single variable, enclose the exponent in curly braces. Consider
x^2or
e^{ \sqrt{\frac{q}{c}} }.
\documentclass[12pt]{article}
Use \frac with the numerator and denominator in curly braces. For example,
\frac{1}{2}.
For Greek letters, use a backslash and the correct spelling of the Greek letter. Start the name of the letter with a capital if you want a capital Greek letter, for example
\deltaor
\Delta.
Use the standard keyboard keys for parentheses and square brackets. For curly braces, use hit the backslash before the keyboard key, as \{ or \}. Grouping symbols can be made larger as needed by preceeding them with backslash and "left" or "right", as in
\frac{d}{dx}\left( c \frac{du}{dx} \right).
{\em This is important.}
For the "partial" symbol, use \partial. For example,
\partial xor
\frac{\partial u}{\partial x}.
The keyboard key for quotation marks gives closing quotation marks in LaTeX. To open the quotes, hit the backquote key twice, as in
``Equilibrium" means unchanging in time.
For the "square-root" symbol, use \sqrt, and enclose the expression in curly braces that goes under the radical. For example,
\sqrt{x}.
To create a subscript, use the underscore key. If the expression in the subscript is more than a single variable, enclose the subscript in curly braces. Consider
u_hor
u_{homog}.
\begin{eqnarray} u(x, y) & = & xy, \\ v(x, y) & = & x + y. \end{eqnarray}