rt
公式如下:
\begin{equation} \label{eq1}
\begin{split}
&a_{1}b_{1}+a_{2}b_{2}+a_{3}b_{3}+\cdots+a_{n}b_{n}\
&=(b_{1}-b_{2})a_{1} \
&+(b_{2}-b_{3})(a_{1}+a_{2}) \
&+(b_{3}-b_{4})(a_{1}+a_{2}+a_{3}) \
&+\cdots \
&+(b_{n-1}-b_{n})(a_{1}+a_{2}+a_{3}+\cdots +a_{n-1}) \
&+b_{n}(a_{1}+a_{2}+a_{3}+\cdots +a_{n})
\end{split}
\end{equation}
