方程与方程组

在公式内容中：在每一行中插入 & 来指定需要对齐的内容，在每行结尾处使用 \\ 换行。

\begin{cases}
3x + 5y + z \\
7x - 2y + 4z \\
-6x + 3y + 2z
\end{cases}

$$\begin{cases} 3x + 5y + z \\ 7x - 2y + 4z \\ -6x + 3y + 2z \end{cases}$$

条件表达式

f(n) =
\begin{cases}
n/2, & \text{if } n \text{ is even} \\
3n+1, & \text{if } n \text{ is odd}
\end{cases}

$$f(n) = \begin{cases} n/2, & \text{if } n \text{ is even} \\ 3n+1, & \text{if } n \text{ is odd} \end{cases}$$

多行等式

\begin{aligned}
f(x) & = (a+b)^2\\
& = a^2+2ab+b^2
\end{aligned}

$$\begin{aligned} f(x) & = (a+b)^2\\ & = a^2+2ab+b^2 \end{aligned}$$

\begin{array}{lcl}
z & = & a \\
f(x,y,z) & = & x + y + z
\end{array}

$$\begin{array}{lcl} z & = & a \\ f(x,y,z) & = & x + y + z \end{array}$$