\item Obtain the one-to-one function $f_1$ and $f_2$ by cutting the graph of $f$ at
a certain point ($x_1$, $y_1$) so that domain of ($f_1$)=($-∞$ , $x_1$] and
domain ($f_2$)=[$x_1$,$+∞$)
2 Answers
A better style is:
Obtain the one-to-one function $f_1$
and $f_2$
by cutting the graph of $f$
at
a certain point $(x_1, y_1)$
so that domain of $(f_1)=(-\infty , x_1]$
and
domain $(f_2)=[x_1,+\infty)$
(Please compare the obtained spacing).
If you are still faced with such a problem, as the last resort, you can use the rotated eight as follows.
\documentclass[preview,border=12pt]{standalone}
\usepackage{graphicx}
\def\infinity{\rotatebox{90}{8}}
\begin{document}
$(-\infinity, x_1]$
\end{document}
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1
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6
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3
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Some fonts have a
\infty
that really looks like a rotated 8 instead of a distinct design.– lblbOct 14, 2017 at 15:48
\infty
\(f_1\)
and\[f_1\]
than$f_1$
and$$f_1$$
. For more information, see this question: tex.stackexchange.com/questions/503/why-is-preferable-to or read about it in l2tabu.\( ... \)
rather than$ ... $
to delimit inline math. Indeed, since\(
and\)
are not "robust" commands (in the LaTeX sense of the word "robust"), it's perilous to use them in the arguments of "moving" commands; no such difficulties arise with$
. Note that the link you provide regards the use of$$
-- a rather different matter.\(\)
either, though I had thought it talked about line spacing a bit. Oh well, ignore my comment (although I'd still go with the LaTeX way unless you need to put it in a moving argument for some reason).