% exp(-t)
   \SCALEVARIABLEfunction
       {-1}{\EXPfunction}
       {\NEGEXPfunction}

% exp(-t)cos(t)
   \PRODUCTfunction
       {\NEGEXPfunction}
       {\COSfunction}
       {\NEGEXPCOSfunction}

% 3t^2-2exp(-t)cos(t)
   \LINEARCOMBINATIONfunction
       {3}{\SQUAREfunction}
      {-2}{\NEGEXPCOSfunction}
      {\myfunction}

\myfunction{5}{\sol}{\Dsol}

If
\[
    f(t)=3t^2-2\mathrm{e}^{-t}\cos t
\]
then
\[
\begin{gathered}
    f(5)=\sol\\
    f'(5)=\Dsol
\end{gathered}
\]