\documentclass[12pt,openany]{book}
\usepackage{extsizes}
\renewcommand{\baselinestretch}{1.2}
\usepackage[
top=1.75cm, % Top margin
bottom=3.5cm, % Bottom margin
left=3.25cm, % Left margin
right=3.25cm, % Right margin
footskip=2.5cm, % footskip margin
]{geometry}
\usepackage[utf8]{inputenc}
\usepackage[T1]{fontenc}
\usepackage{tikz}
\usepackage{microtype}
\usepackage[none]{hyphenat}
\usepackage{multicol}
\usepackage{hyperref}
\hypersetup{pdfpagemode={UseOutlines},
bookmarksopen=true,
bookmarksopenlevel=0,
hypertexnames=false,
colorlinks=true,% Set to false to disable coloring links
citecolor=magenta,% The color of citations
linkcolor=black,% The color of references to document elements (sections, figures, etc)
urlcolor=mdtRed,% The color of hyperlinks (URLs)
pdfstartview={FitV},
unicode,
breaklinks=true,
}
\usepackage{enumitem}
\usepackage{nameref}
\usepackage{amsfonts,amsmath,amssymb,amsthm,etoolbox}
\newtheoremstyle{custom}% name
{12pt}% Space above
{3pt}% Space below
{\parshape 3 0pt \textwidth \parindent \dimexpr\textwidth-\parindent 0pt \textwidth}% Body font
{}% Indent amount
{\bfseries}% Theorem head font
{}% Punctuation after theorem head
{\newline}% Space after theorem head
{\thmname{#1}\thmnumber{ #2}{\mdseries\thmnote{ [#3]}}}% Theorem head spec(can be left empty, meaning ‘normal’)
\theoremstyle{custom}
\swapnumbers
\newtheorem{theo}{Teorema}[section]
\newenvironment{thm}
{\pushQED{\qed}\renewcommand{\qedsymbol}{$\square$}\thmx}
{\popQED\endthmx}
\newtheorem*{demostracion}{Demostración}
\newtheorem{definition}{Definición}[section]
\newtheorem{pro}{Proposición}[section]
\usepackage{MnSymbol}
\usepackage{wasysym}
\usepackage{float}
\setlength{\parindent}{1em}
\setlength{\parskip}{0.8em}
\renewcommand\rmdefault{cmr}
\renewcommand\sfdefault{cmss}
\renewcommand\ttdefault{cmtt}
\usepackage[gen]{eurosym}
\usepackage{titlesec}
\setcounter{secnumdepth}{4}
\renewcommand{\chaptername}{Tema}
\usepackage{titlesec, blindtext, color}
\definecolor{gray75}{gray}{0.75}
\newcommand{\hsp}{\hspace{20pt}}
\titleformat{\chapter}[hang]{\Large}{\textbf{\chaptername $~$ \thechapter.} }{0pt}{\Large}
\newcommand{\Mysquare}{\raisebox{.25\height}{\tiny$\square$}}
%\newcommand{\Mysquare}{\square}
\usepackage{fancyhdr}
% Set the page style to "fancy"...
\pagestyle{fancy}
%... then configure it.
\fancyhead{} % clear all header fields
\renewcommand{\chaptermark}[1]{\markboth{#1}{#1}}
\fancyhead[L]{}
\fancyhead[R]{\chaptername\ \thechapter\ --\ \leftmark}
%\fancyhead[RO,LE]{\textbf{The performance of new graduates}}
%\fancyfoot{} % clear all footer fields
\fancyfoot{}
\fancyfoot[c]{\thepage}
\fancyfoot[l]{OPOSICIONES}
\fancyfoot[r]{Azahara Carpintero}
\fancypagestyle{plain}{%
\fancyfoot[c]{\thepage}
\fancyfoot[l]{left}
\fancyfoot[r]{right}
}
\renewcommand{\headrulewidth}{0.4pt}
\renewcommand{\footrulewidth}{0.4pt}
\usepackage{xcolor,graphicx,eso-pic}
\usepackage{lipsum}
\usepackage{transparent}
%\usepackage{mtpro2}
\newcommand*{\Scale}[2][4]{\scalebox{#1}{$#2$}}%
\newcommand*{\Resize}[2]{\resizebox{#1}{!}{$#2$}}%
\usepackage{wrapfig}
\usepackage[none]{hyphenat}
\begin{document}
\sloppy
\chapter{Dumy Chapter}
\section{Dumy Section}
\begin{definition}[\bfseries De límite infinito]
\begin{minipage}[t]{0.6\textwidth}
\textit{Sea $f$ una función, real de variable real, definida al menos en un entorno reducido $U^{*}$ de un punto $a \in \mathbb{R}$. Se dice que $f$ tiene límite $+\infty$ (límite $-\infty$) en el punto $a$ y se pone $\lim _{x \rightarrow a} f(x)= + \infty$ \quad ($\lim _{x \rightarrow a} f(x)= - \infty$) si para cada número real $k>0$ eriste otro $\delta > 0$ tal que si $x \in U^{*}$ y $0 < \mid x-a \mid < \delta$, entonces es $f(x) > k$ (es $f(x) < -k$).}
\end{minipage}\hfill
\begin{minipage}[t]{0.4\textwidth}
\centering\raisebox{\dimexpr \topskip-\height}{%
\includegraphics[width=5.0cm]{fig-45}}
\end{minipage}
\end{definition}
\end{document}
答案1
只需更换
{\parshape 3 0pt \textwidth \parindent \dimexpr\textwidth-\parindent 0pt \textwidth}
和
{}
并且，一定要用\mid x-a \mid替换|x-a|。