单个编号连等式的 LaTeX 写法如下：
%%%%%% Equations %%%%%%
\begin{align}L & = (a + b)^2 \nonumber \\& = a^2 + 2ab + b^2
\end{align}
LaTex渲染结果如下：
L = ( a + b ) 2 = a 2 + 2 a b + b 2 \begin{align} L &= (a + b)^2 \nonumber \\ &= a^2 + 2ab + b^2 \end{align} L=(a+b)2=a2+2ab+b2
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