Latex Tutorial 2
1) Note: Latex is case sensitive.
2) To underline something, you use underline{ }. To overline something, you use \overline{ }.
3) To write the mathematical symbol of infinity, you use \infty.
4) If you want to define your own function and use it in a formula, you need to include the following before "begin document" (here, the name of the function I'm using is sinc):

\usepackage{amsmath}
\newcommand{\sinc}{\operatorname{sinc}}

5) To write an array, you do the following (here the array has 3 columns and the text in each column is written in the center):

\left(
\begin{array}{ccc}
1 & 2 & 3 \\
4 & 5 & 6 
\end{array}
\right)

Note that {ccc} indicates that the array has 3 columns and the text in each column is in the center. You may use l or r instead of c (l for left, r for right, and c for center).

The elements in each column are separated by & and each row is separated from other rows by \\.

\left( is used to write a left parenthesis to the left of the array and \right) is used to write a right parenthesis. You may instead use \left[ and \right].

6) If an equation or an inequality extends to more than one line, you need to use an array style to do that because the equality/inequality in each line must be below the equality/inequality in the previous line. Here is an example:

\begin{eqnarray*}
x & = & 1 + 2 + 3 + 4 \\
  & = & 10.
\end{eqnarray*}

Note that \\ is used to go to the next line.

Instead of eqnarray*, you may use eqnarray. The last one numbers the equations while the first does not.

7) For tables, you use

\begin{tabular}{|c|c|}
\hline
1 & 2 \\
\hline
\end{tabular}

cc is used to indicate that there are two columns and the text in each column is written in the center. Again, you may use l or r instead of c. Using c|c implies that two comuns will be separated by a line. Using |cc means there will be a line to the left of the first column. Uisng cc| means there will be a line to the right of the last column.

\\ is used to go to the next row of the table. To insert a line between one row and another, you use \hline.