\documentclass[12pt]{article}
\usepackage{fontspec}
\usepackage{stackengine}
\usepackage{amsmath}
\usepackage{cancel}
\usepackage{amssymb}
\usepackage{dsfont}
\usepackage{amsfonts} 
\usepackage{wrapfig}
\usepackage{graphicx}
\usepackage{pifont}
\usepackage{hyperref}
\usepackage[margin=0.4in]{geometry}
\newcommand{\cmark}{\ding{51}}%
\newcommand{\xmark}{\ding{55}}%
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\newcommand\e\exists
\newcommand\all\forall
\newcommand\la\langle
\newcommand\ra\rangle
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\newcommand\eps\varepsilon
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\newcommand\Dx{\Delta x}
\newcommand\Dy{\Delta y}
\newcommand\ph\varphi
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\newcommand\ntab{\\\hspace*{1cm}}
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\newcommand\prll\parallel
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\renewcommand*\contentsname{Содержание}
\renewcommand{\ss}[1]{\left\{{#1}\right\}}
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\setmainfont{FreeSans}
\graphicspath{ {../images} }
\stackMath
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% \everymath{\displaystyle}
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\DeclareMathOperator{\tg}{tg}
\DeclareMathOperator{\adj}{adj}
%\DeclareMathOperator{\arcsin}{arcsin}
\author {\texttt{justanothercatgirl}}