Tex数学公式示例

$\frac{2}{5} \div \frac{{16}}{{25}} = \frac{2}{5} \times \frac{{25}}{{16}} = \frac{{\mathop {\not 2}\limits^1 }}{{\mathop {\not 5}\limits_1 }} \times \frac{{2\mathop {\not 5}\limits^5 }}{{\mathop {1\not 6}\limits_8 }} = \frac{5}{8}$

$x_{1,2}  = \frac{{ - b \pm \sqrt \Delta  }}{{2a}} $

$\mathop {\lim }\limits_{x \to \infty } \frac{{{\text{sinx}}}}{x} = 1$

$\int\limits_1^3 {xdx}  = \frac{1}{2}x^2 \left| {_1^3 } \right. = \frac{1}{2} \times 3^2  - \frac{1}{2} \times 1^2  = 4$

$f(x)=\left\{\begin{matrix} & \frac{\cos x}{x+\sin x} & &x \geq 0& \\  & ax^2+bx+c &    &x < 0 & \end{matrix}\right.$