Using David's suggestion, I used
\let\oldtabular\tabular
\let\oldendtabular\endtabular
\def\tabular{\setlength{\lineskiplimit}{0pt}\oldtabular}
\def\endtabular{\oldendtabular\setlength{\lineskiplimit}{-10pt}}
which more or less seems to fix the problem. If anyone has a more elegant/better solution, please let me know!
Apparently tblr doesn't like environments in X cells.
\documentclass[12pt]{article}
\usepackage{amsmath}
\usepackage{amssymb}
\usepackage{ninecolors}
\usepackage{tabularray}
\UseTblrLibrary{siunitx}
\UseTblrLibrary{counter}
\sisetup{output-decimal-marker={,}}
\DefTblrTemplate{contfoot-text}{normal}{Continued on next page}
\SetTblrTemplate{contfoot-text}{normal}
\DefTblrTemplate{conthead-text}{normal}{(Continued)}
\SetTblrTemplate{conthead-text}{normal}
\SetTblrTemplate{conthead-text}{normal}
\newcounter{mycnta}
\newcommand{\mycnta}{\stepcounter{mycnta}\arabic{mycnta}}
\newcommand{\hackequation}[1]{%
\unskip\vspace{0.5\abovedisplayskip}\newline
\makebox[\linewidth]{$\displaystyle#1$}\vspace{0.5\belowdisplayskip}%
}
\begin{document}
\begin{longtblr}[caption={Some text}]
{
colspec = {Q[c,gray9]X[l]Q[c]},
vlines,
hlines,
row{1}={yellow9,font=\bfseries},
cell{2,7,11}{2-3} ={teal9},
%cell{7}{2-3} ={teal9},
%cell{11}{2-3} ={teal9},
hline{1,2,Y,Z} = {solid},
cell{1}{2-3}={halign=c},
column{1}={font=\bfseries},
cell{2-Z}{1}={cmd={\mycnta}},
}
Problem & Content & Point \\
\SetCell[r=5]{m} &
Solve the equation\hackequation{
(2 x+3)\cdot \sqrt{4 x+5}+(6 x+7) \cdot\sqrt{8 x+9}=2.
} & \num{1.00} \\
& $ \Delta =(-5)^2 - 4 \cdot 1 \cdot 6 = 1$, & \num{0.25} \\
& $ x = \dfrac{-(-5) -1}{2} = 2$. & \num{0.25} \\
& $ x = \dfrac{-(-5) + 1}{2} = 3$ & \num{0.25} \\
& The given equation has two solutions $x=2$ and $x = 3$. & \num{0.25} \\
\end{longtblr}
\end{document}
It's also possible, if really needed, to number the equation and to cross-reference it.
\documentclass[12pt]{article}
\usepackage{amsmath}
\usepackage{amssymb}
\usepackage{ninecolors}
\usepackage{tabularray}
\UseTblrLibrary{siunitx}
\UseTblrLibrary{counter}
\sisetup{output-decimal-marker={,}}
\DefTblrTemplate{contfoot-text}{normal}{Continued on next page}
\SetTblrTemplate{contfoot-text}{normal}
\DefTblrTemplate{conthead-text}{normal}{(Continued)}
\SetTblrTemplate{conthead-text}{normal}
\SetTblrTemplate{conthead-text}{normal}
\newcounter{mycnta}
\newcommand{\mycnta}{\stepcounter{mycnta}\arabic{mycnta}}
\newcommand{\hackequation}[1]{%
\unskip\vspace{0.5\abovedisplayskip}\newline
\parbox{\linewidth}{%
\setlength{\abovedisplayshortskip}{0pt}%
\setlength{\belowdisplayshortskip}{0pt}%
\noindent\begin{equation}#1\end{equation}%
}\vspace{0.5\belowdisplayskip}%
}
\begin{document}
\begin{longtblr}[caption={Some text containing \eqref{test}}]
{
colspec = {Q[c,gray9]X[l]Q[c]},
vlines,
hlines,
row{1}={yellow9,font=\bfseries},
cell{2,7,11}{2-3} ={teal9},
%cell{7}{2-3} ={teal9},
%cell{11}{2-3} ={teal9},
hline{1,2,Y,Z} = {solid},
cell{1}{2-3}={halign=c},
column{1}={font=\bfseries},
cell{2-Z}{1}={cmd={\mycnta}},
}
Problem & Content & Point \\
\SetCell[r=5]{m} &
Solve the equation\hackequation{\label{test}
(2 x+3)\cdot \sqrt{4 x+5}+(6 x+7) \cdot\sqrt{8 x+9}=2.
} & \num{1.00} \\
& $ \Delta =(-5)^2 - 4 \cdot 1 \cdot 6 = 1$, & \num{0.25} \\
& $ x = \dfrac{-(-5) -1}{2} = 2$. & \num{0.25} \\
& $ x = \dfrac{-(-5) + 1}{2} = 3$ & \num{0.25} \\
& The given equation has two solutions $x=2$ and $x = 3$. & \num{0.25} \\
\end{longtblr}
\end{document}
Best Answer
You can use the
expandoption.I think only one such macro can be expanded per
table. It must be defined with\newcommand, not with\NewTableCommand.