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\begin{document}
\huge

$$A\stackrel{\rm def}{=}\{x \| x>0 \}$$
$x+y\times z $\\
$x+y\otimes z $
$y_1 \prime $\\
$y_2 \prime \prime \prime $\\
$y_3 \prime \prime \prime $


$$ f(x)=\left\{{{1\over q}\atop 0}
\hskip 2cm {x={p\over q}\atop otherwise}
\right\}$$\\
$$\Bigg(\bigg(
\Big(\big(()
\big)\Big) \bigg)\Bigg)$$\\
$$\bigg({n\atop k} \bigg)$$\\


$$x={c\choose k}$$
$${n\choose k} \over 2$$
$${s\choose{ k\over 2}} $$
$\sum_{i=1}^{k}a_i$\\
$ 0 \not \in A, B \not \subset  X ,j, a \not  \equiv b  $
$$\int_{0}^{1} f(x) dx$$


\setcounter{equation} {6}
\begin{equation}
a=b
\end{equation}\\
\begin{equation}
a+c=b+d\qquad*c=b*d
\end{equation}\\
\begin{equation}
c=d
\end{equation}\\
$\lim_{n\rightarrow \infty}$
$\int_{0}^{+\infty}f(x) dx $\\
${\sin^2} x+{\cos^2}x=1$

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