字符串：
\(\rm{aaa}\)
\rm{aaa}
多行对齐：
\(\begin{aligned} f(x) & = (m+n)^2 \\ & = m^2+2mn+n^2 \\ \end{aligned}\)
\begin{aligned}
f(x) & = (m+n)^2 \\
& = m^2+2mn+n^2 \\
\end{aligned}
方程组：
\(\begin{cases} 3x + 5y + z \\ 7x - 2y + 4z \\ -6x + 3y + 2z \\ \end{cases}\)
\begin{cases}
3x + 5y + z \\
7x - 2y + 4z \\
-6x + 3y + 2z
\end{cases}