latex练习

99+2-1=100 \\
x^2+2x+5+\sqrt x=0 \\
$$\begin{cases} x+y+z=10 \\ x+2y+3z=20 \\ x+4y+5z=30 \end{cases}$$ \\
\sum_{i=1}^{N}2i+1 \\
\prod\limits_{i=1}^n{2i} \\
\frac{1}{2x^2+2ax+1} \\
9 \times 8 = 72 \\
5 \cdot 6 = 30 \\
30 \div 6 = 5 \\
y= $$\begin{cases} x^2, & x>0 \\ x^2+x-8, & x \le 6 \\ x^3, & other \\ \end{cases}$$ \\
A=\left[
$$\begin{array}{c c c : c} 1 & 2 & 3 & 4 \\ 5 & 6 & 7 & 8 \\ 9 & 10 & 11 & 12 \\ \end{array}$$
\right] \\
欧拉方程：& e^{i\pi}+1=0 \\
质能守恒：& E=mc^2 \\
万有引力：& F=G \frac {m_1 m_2}{R^2} \\
麦克斯韦方程组： \\
$$\begin{array}{lll} \nabla\times E &=& -\;\frac{\partial{B}}{\partial{t}} \\ \ \nabla\times H &=& \frac{\partial{D}}{\partial{t}}+J \\ \ \nabla\cdot D &=& \rho \ \nabla\cdot B &=& 0 \ \end{array}$$ $ \\

薛定谔方程：\\
\hbar\frac
{\partial \psi}
{\partial t}
= \frac{-\hbar^2}{2m} \left(\frac{\partial^2}
{\partial x^2} + \frac{\partial^2}
{\partial y^2}+\frac{\partial^2}
{\partial z^2}
\right) \psi + V \psi$

语调符号：\\
\text{\={a}} & 一声\\
\text{\'{a}} & 二声\\
\text{\v{a}} & 三声\\
\text{\`{a}} & 四声\\
\text{\u{a}} & \\
\text{\~{a}} & \\
\text{\.u{a}} & \\
\text{\^{a}} & \\
\text{\"{a}} & \\
\text{\r{a}} & \\
\text{a} & 轻声\\