to compile Tex, I use latex/pdftex version of LaTex. Here are some details
pdfTeX 3.14159265-2.6-1.40.20 (TeX Live 2019/Debian)
kpathsea version 6.3.1
Copyright 2019 Han The Thanh (pdfTeX) et al.
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Primary author of pdfTeX: Han The Thanh (pdfTeX) et al.
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Compiled with xpdf version 4.01
My problem is, if I want a newline in either \begin{equation} or $$, the operator \\ does not work. How do I sperate lines? In other forms of Tex, the \\ seperates the lines of such as
$$
<expression1> \\ <expression2>
$$
It should seperate in two lines but it does not.
\\should not make a newline inequationwhich is a single line equation environment. Usealignorgatherfromamsmathpackage for multi-line equations. – David Carlisle Jan 06 '21 at 14:18$$should not be used in latex at all, independent of\\see https://tex.stackexchange.com/questions/503/why-is-preferable-to/69854#69854 – David Carlisle Jan 06 '21 at 14:37