flalign environment inside a tcolorbox

Question

I've build a flalign environment and I'm happy with the result, but now I want to put it in a tcolorbox like in my example. I can't figure out how I can make that possible.

This is my MWE

\documentclass[preview]{standalone}
\usepackage{array,tabularx,calc}
\usepackage[dutch]{babel}
\usepackage{tcolorbox}
\tcbuselibrary{theorems}

\pagestyle{empty}

\definecolor{yourcolor}{RGB}{128, 0, 0}

\newlength{\conditionwd}
\newenvironment{conditions}[1][\\ \textbf{Waarin} \\\\]
  {%
   #1\tabularx{11cm}[t]{@{}
     >{$}l<{$} @{${}={}$} X@{} >{[}>{$}r<{$}<{]}
                        }%
  }
  {\endtabularx\\[\belowdisplayskip]}

\begin{document}
    \begin{tcolorbox}[ams align,colback=yellow!10!white,colframe=yourcolor]
    f(x) & = {} g(x)
    \end{tcolorbox}
    \begin{flalign}
    q_{as} = \frac{(m_{as} \cdot g)}{L_{ac}} &&
    \end{flalign}
    \begin{conditions}
    q_{as}  &   Verdeelde belasting door de as  &   N \cdot mm\\
    m_{as}  &   Massa van de aandrijfas         & kg \\
    g       &   gravitatieconstante             & m/s^2 
    \end{conditions}
\end{document}

which gives me this result;

The tcolorbox(not overruling textwidth) is the one I want, but with the flalign and conditions in it.

Is there someone who can help me out?

Thank you in advance!

Answer 1

Why not a single flalign for both equations?

\documentclass[preview, border = 12pt]{standalone}
\usepackage{array,tabularx,calc}
\usepackage[dutch]{babel}
\usepackage{tcolorbox}
\tcbuselibrary{theorems}

\pagestyle{empty}

\definecolor{yourcolor}{RGB}{128, 0, 0}

\newlength{\conditionwd}
\newenvironment{conditions}[1][\\ \textbf{Waarin} \\\\]
  {%
   #1\tabularx{11cm}[t]{@{}
     >{$}l<{$} @{${}={}$} X@{} >{[}>{$}r<{$}<{]}
                        }%
  }
  {\endtabularx\\[\belowdisplayskip]}

\begin{document}
    \begin{tcolorbox}[colback=yellow!10!white,colframe=yourcolor]%
 \begin{flalign}
   & & f(x) & = {} g(x) & & \\
    q_{as} = \frac{(m_{as} \cdot g)}{L_{ac}} &&
 \end{flalign}
    \begin{conditions}
    q_{as} & Verdeelde belasting door de as & N \cdot mm\\
    m_{as} & Massa van de aandrijfas & kg \\
    g & gravitatieconstante & m/s^2
    \end{conditions}
    \end{tcolorbox}

\end{document} 

Answer 2

Nice, thank you!

The first equation was only to show you a working tcolorbox example. When I built something like this:

\begin{tcolorbox}[ams align, colback=yellow!10!white,colframe=yourcolor]%
    \begin{flalign}
    q_{as} = \frac{(m_{as} \cdot g)}{L_{ac}} &&
    \end{flalign}
    \begin{conditions}
    q_{as}  &   Verdeelde belasting door de as  &   N \cdot mm\\
    m_{as}  &   Massa van de aandrijfas         & kg \\
    g       &   gravitatieconstante             & m/s^2 
    \end{conditions}
\end{tcolorbox}

I get the error; !Argument of \flalign has an extra }.<inserted text>\par\end{tcolorbox}

But I see from your example that the problem was in the ams align of my tcolorbox. I don't know why that's forming a problem, but problem solved by removing it.

Thanks.