\documentclass{book}
\usepackage[all]{xy}
\usepackage{amsthm,amssymb,amsmath,mathrsfs,amsfonts}
\begin{document}
\begin{equation}
\begin{gathered}
\int d^3\vec{q}_2 d^3\vec{q}_2 \mathit{f}_{2,3}\\ 
 b_2=\xymatrix{\bullet\ar@{.}[r]&\bullet  }=\int d^3\vec{q}_1 d^3\vec{q}_2 \mathit{f}(\vec{q}_1-\vec{q}_2)
\end{gathered}
\end{equation}

\begin{align}
        \begin{split}
        10 =1&+2 \\
                &+3+4 \\
                &+5+6 \\
                &+7+8 
        \end{split} \\
            =& 4x - 5
    \end{align}

\end{document}