差分

\[mp+Mq=\int^t_0(f(t)+g(t))dt-(f(0)+g(0))t

\]

g &=&\frac{mp+Mq}{m+M}\\

&=&\frac1{m+M}\left(\int^t_0(f(t)+g(t))dt-(f(0)+g(0))t\right)

\end{eqnarray*}