LaTeX Forum

\documentclass[12pt, twoside, openright, fleqn]{scrreprt}

\usepackage{amsmath}

\begin{document}
\begin{align*}
xxx
\textbf{\emph{x}}
\emph{\textbf{x}}
\end{align*}
\end{document}

\documentclass[12pt, twoside, openright, fleqn]{scrreprt}
\usepackage{amsmath}
\DeclareMathAlphabet      {\mathbfit}{OML}{cmm} {bx}{it}
% oder
%\DeclareMathAlphabet      {\mathbfit}{OT1}{cmr}{bx}{it}
\begin{document}
\begin{align*}
 xxx\mathbfit{x}
\end{align*}
\end{document}