\documentclass{article}
\usepackage{amsmath}
\begin{document}

% Integral $\int_{a}^{b} x^2 \,dx$ inside text

% Hello $m_1 m_2$ world \textit{příliš žluťoučký}\textbf{úpěl}


\[
    \binom{n}{k} = \frac{n!}{k!(n-k)!}
\]

\[ 
  x = a \times \left( \frac{c}{\frac{d}{x}}\right )
\]
\[
  a_0+\cfrac{1}{a_1+\cfrac{1}{a_2+\cfrac{1}{a_3+\cdots}}}
\]

\[ \sqrt{a^2 + b^2}\]


${a+2 \over b^2} \times \sin{a} $

$  1 + \frac{a}{b} + 2$

$  1 + \begingroup a \over b \endgroup + 2$

$  1 + \bgroup a \over b \egroup + 2$

$  1 + { a \over b \egroup + 2$


$  1 + \bgroup a \over b } + 2$

$ { a + b \over {c \over d}}$

\[ { a + b \over {c \over d}}\]

\[
  F = G \left( \frac{m_1 m_2}{r^2} \right)
\]

\[
    \lim_{h \to 0 } \frac{f(x+h)-f(x)}{h}
.\]

Integral $\int_{a}^{b} x^2 \,dx$ inside text

\[ \int_{a}^{b} x^2 \,dx \]

\end{document}
