问题分裂/拟合方程

Question

我正在努力解决一个超出页面的方程式，因为它太长了。我已经读到最好的解决方案是拆分方程式，所以我尝试使用 {multline} 或 {split}，但我一直出错。有人能帮我吗？

    \begin{equation}
\begin{aligned}
i\to -\frac{-c \left(\beta  (-2 \gamma -\delta +\nu )+\sqrt{\beta ^2 (\delta +\mu )^2+c^2 (\nu +\mu )^2+2 \beta  c (\nu +\mu ) (2 \gamma +\delta +\mu )}\right)+\beta  \left(\beta  \delta +\beta  \mu +\sqrt{\beta ^2 (\delta +\mu )^2+c^2 (\nu +\mu )^2+2 \beta  c (\nu +\mu ) (2 \gamma +\delta +\mu )}\right)+c^2 (\nu +\mu )}{2 \beta ^2 c}
\end{aligned}
\end{equation}

谢谢 ：-）

Answer 1

我会重新组织这些术语并避免出现大比例的情况：

\documentclass{article}
\usepackage{amsmath}

\begin{document}

\begin{equation}
\begin{split}
i\to \frac{1}{2 \beta^2 c}
\Bigl(
& c\sqrt{\beta ^2 (\delta +\mu )^2+c^2 (\nu +\mu )^2
         +2 \beta  c (\nu +\mu ) (2 \gamma +\delta +\mu )}
\\
& -\beta\sqrt{\beta ^2 (\delta +\mu )^2+c^2 (\nu +\mu )^2
    +2 \beta  c (\nu +\mu ) (2 \gamma +\delta +\mu )}
\\
& +c\beta (-2 \gamma -\delta +\nu )
  -\beta^2 (\delta + \mu)
  -\beta c^2 (\nu +\mu )
\Bigr)
\end{split}
\end{equation}

\end{document}

Answer 2

这里有两种可能性（+一种变体），为其中型命令加载mathtools for the多行environment and thesplitfrac nccmath`，并以各种方式组合它们：command, and

\documentclass{article}
\usepackage[showframe]{geometry}
\usepackage{mathtools, nccmath}

\begin{document} %

 \begin{equation}
\begin{multlined}[b]i\to -\frac1{2 \beta ^2 c}\biggl[(-c \Bigl(\beta (-2 \gamma -\delta +\nu )+\sqrt{\beta ^2 (\delta +\mu )^2+c^2 (\nu +\mu )^2+2 \beta c (\nu +\mu ) (2 \gamma +\delta +\mu )}\Bigr) \\+\beta \Bigl(\beta \delta +\beta \mu +\sqrt{\beta ^2 (\delta +\mu )^2+c^2 (\nu +\mu )^2+2 \beta c (\nu +\mu ) (2 \gamma +\delta +\mu )}\Bigr)+c^2 (\nu +\mu )\biggr]
\end{multlined}
\end{equation}
\bigskip
 \begin{equation}
\begin{aligned}
i\to -\frac{\medmath{\splitfrac{-c \left(\beta (-2 \gamma -\delta +\nu )+\sqrt{\beta ^2 (\delta +\mu )^2+c^2 (\nu +\mu )^2+2 \beta c (\nu +\mu ) (2 \gamma +\delta +\mu )}\right) + }{\beta \left(\beta \delta +\beta \mu +\sqrt{\beta ^2 (\delta +\mu )^2+c^2 (\nu +\mu )^2+2 \beta c (\nu +\mu ) (2 \gamma +\delta +\mu )}\right)+c^2 (\nu +\mu )}}}{2 \beta ^2 c}
\end{aligned}
\end{equation}
\bigskip
 \begin{equation}
\begin{aligned}
i\to \medmath{-\frac{\splitfrac{-c \left(\beta (-2 \gamma -\delta +\nu )+\sqrt{\beta ^2 (\delta +\mu )^2+c^2 (\nu +\mu )^2+2 \beta c (\nu +\mu ) (2 \gamma +\delta +\mu )}\right) + }{\beta \left(\beta \delta +\beta \mu +\sqrt{\beta ^2 (\delta +\mu )^2+c^2 (\nu +\mu )^2+2 \beta c (\nu +\mu ) (2 \gamma +\delta +\mu )}\right)+c^2 (\nu +\mu )}}{2 \beta ^2 c}}
\end{aligned}
\end{equation}

 \end{document}