## Multiple Line Equations

line break

$\begin{eqnarray} aaa \\ bbb \end{eqnarray}$

\begin{eqnarray}
aaa \\
bbb
\end{eqnarray}

To display a multi-line expression, we use the eqnarray environment. A line break is not reflected in the expression. To start a new line, we put "\\".

big line break

$\begin{eqnarray} aaa \\[5pt] bbb \end{eqnarray}$

\begin{eqnarray}
aaa \\[5pt]
bbb
\end{eqnarray}

You can change the size of a line break by using square brackets after "\\", e.g. \\[5pt].

alignment

$\begin{eqnarray} x + 2x &=& 3 \\ x &=& 1 \end{eqnarray}$

\begin{eqnarray}
x + 2x &=& 3 \\
x &=& 1
\end{eqnarray}

You can use "&" to align the position.

simultaneous equations

$\begin{eqnarray} \left\{ \begin{array}{l} x + y = 10 \\ 2x + 4y = 32 \end{array} \right. \end{eqnarray}$

\begin{eqnarray}
\left\{
\begin{array}{l}
x + y = 10 \\
2x + 4y = 32
\end{array}
\right.
\end{eqnarray}

You can use "\left\{" and "\right." to represent the big curly bracket on the left side of the simultaneous equations.

case

$\begin{eqnarray} |x| = \begin{cases} x & ( x \geqq 0 ) \\ -x & ( x \lt 0 ) \end{cases} \end{eqnarray}$

\begin{eqnarray}
|x|
=
\begin{cases}
x & ( x \geqq 0 ) \\
-x & ( x \lt 0 )
\end{cases}
\end{eqnarray}

The cases environment can be used to display for piecewise-defined functions.

Formula
Symbol
Text
Other