Equation 24.4.21B755FCE3BC15

\begin{equation} \left.\frac{\mathrm d}{\mathrm dt}\right|_{t=0} \frac1{n!}\int _ X(Q+t(\mathrm d\xi )^{1,1})^ n =\frac1{(n-1)!}\int _ X\xi \wedge \mathrm dQ^{n-1}, \end{equation}